Search

PURPOSETo evaluate outcome after refractive surgery in cataract patients for whom intraocular lens (IOL) selection was based on the use of a myopic regression formula. METHODSThis prospective case series included 20 eyes of 14 patients who had previous uncomplicated myopic refractive surgery, followed by uncomplicated cataract extraction with IOL implantation. Calculation of IOL was based on flattest keratometry readings, spherical equivalent refraction before refractive surgery, and an adjustment factor derived from the regression formula: -(0.47x + 0.85). Following cataract extraction, refractive error was compared against refractive aim. The power of IOL obtained by the regression formula (IOLRF) was compared to those obtained using the clinical history method at the spectacle plane (IOLHisKs) and the Double-K formula (IOLDoubleK). The results acquired with each technique were compared with those achieved using an IOL back-calculated for emmetropia (IOLexact). RESULTSUsing the regression formula, IOL calculations produced postoperative cataract extraction refractions within 1.00 diopter (D) (range: -1.00 to 0.78 D) of the intended outcome. Mean spherical equivalent refraction after cataract extraction was -0.31±0.56 D. Twelve of 20 eyes had sufficient data to evaluate the statistical relationships among the three formulas compared with IOLexact. Paired t test results revealed IOLRF (P=.0932) and IOLHisKs (P=.9955) were not statistically different from IOLexact whereas IOLDoubleK was statistically different from IOLexact (P=.0008). CONCLUSIONSThe myopic regression formula is recommended for postoperative myopic LASIK IOL selection to provide a simple, accurate, and consistent method of predicting IOL calculation that is not statistically different from IOLexact. [J Refract Surg. 2008;24:33-38.] ABOUT THE AUTHORS From Laser and Corneal Surgery Associates PC and the Department of Ophthalmology, New York Eye and Ear Infirmary, New York, NY (Khalil, Latkany, Speaker); the Department of Ophthalmology, University of Florida, Jacksonville, Fla (Chokshi); and the Department of Otolaryngology, Biostatistics and Epidemiology Service, New York Eye and Ear Infirmary, New York, NY (Yu). Presented at the American Society of Cataract and Refractive Surgery Meeting; March 19, 2006; San Francisco, Calif. Dr Latkany has a patent pending on a myopic and hyperopic regression formula for IOL calculations in post-refractive surgery patients; Sonomed has purchased a nonexclusive right to the use of both formulas. Dr Speaker is a consultant for Alcon Pharmaceuticals. The remaining authors have no proprietary interest in the materials presented herein. Correspondence: Robert Latkany, MD, New York Eye and Ear Infirmary/Laser and Corneal Surgery Associates PC, 115 E 57th St, 10th Floor, New York, NY 10022. Tel: 212.832.2020; Fax: 212.832.9739; E-mail: relief@dryeyedoctor.com Received: September 20, 2006 Accepted: March 6, 2007 Posted online: July 16, 2007

Purpose: To evaluate the normalization of the tear film (tear film normalization test [TNT]) as a diagnostic test for dry eye syndrome. Methods: The uncorrected distance vision of 20 patients with dry eyes (40 eyes) and 20 normals (40 eyes) before and after instillation of carboxymethyl cellulose 0.5% (CMC; Refresh Plus; Allergan, Irvine, CA) was recorded. We used study early treatment diabetic retinopathy (ETDRS) vision charts to test vision in each eye. Tear film breakup time (TBUT), presence or absence of superficial punctate erosions (SPE), tear film meniscus height, meibomian gland ftnction, and ocular surface disease index (OSDI) questionnaire scores were evaluated. Results: CMC improved visual acuity in the dry eye group (P < 0.0001). Response operator's curve (ROC) analysis showed that vision improvement of 2 lines or more after tear normalization was associated with an 82.5% (95% CI: 66.6%-92.1%) sensitivity and 100% (95% CI: 89.1%-100%) specificity for dry eye. There was a significant correlation between vision improvement and OSDI score in the dry eye group (P = 0.003). Conclusion: The TNT is a highly sensitive and specific test for dry eyes and is available in every eye care professional's office. The more symptomatic the dry eye, the greater the improvement.

To study the effect of commonly used preservative free artificial tear, carboxymethylcellulose (CMC) 0.5% (Refresh Plus, Allergan, Irvine, California) on visual acuity in symptomatic dry eye (SDE) and asymptomatic dry eye (ADE) patients.Nonrandomized prospective clinical trial.Prospective study involving 20 patients (40 eyes) with SDE and 20 patients (40 eyes) with ADE, all 40 years and older, were recruited from a clinic setting over a 1-month period. Distance visual acuity was measured by the Early Treatment of Diabetic Retinopathy Study (ETDRS) vision chart and near visual acuity was measured by the Lighthouse Near Vision chart before and 30 seconds after instillation of one drop of CMC. Distance and near visual acuity was measured both with and without correction. The duration of action of CMC was measured at 1-minute intervals until the patient's visual acuity returned to pretear level.In both SDE and ADE groups, uncorrected and corrected near and distance vision showed a statistically significant improvement after the use of CMC (P.05). There was no statistically significant difference in improvement between the SDE and ADE groups in all categories (P values.05). The mean duration of improvement of vision was 2.93 minutes in the SDE group and 3.70 minutes in the ADE group (P = .036).CMC 0.5% provides a temporary yet significant improvement in the visual acuity of SDE and ADE patients. The effect of artificial tears on visual acuity may be of diagnostic value in detecting ocular surface abnormality in symptomatic and asymptomatic patients.

Purpose: To report serious complications caused by recutting laser in situ keratomileusis (LASIK) flaps for enhancement and reconsider the current preferred method of LASIK enhancement. Setting: Multiple surgeon practices. Methods: This retrospective noncomparative nonconsecutive case series comprised LASIK patients in the private practices of 9 experienced refractive surgeons and those reported in a survey of refractive surgeons. Case histories, refractions, corneal topographies, slitlamp photographs, and measurements of uncorrected and best corrected (BCVA) visual acuity after recutting LASIK flaps were collected. Surveys of refractive surgeons and an analysis of changing practice trends among the authors and these surgeons were assessed. Results: In 12 cases, significant loss of BCVA and subjective visual difficulties resulted from recutting LASIK flaps. Most surveyed surgeons had changed their practice from recutting to lifting flaps even 9 to 10 years postoperatively with good results. Conclusion: Recutting flaps for enhancement should be avoided unless other alternatives are unavailable. J Cataract Refract Surg 2003; 29:2306–2317  2003 ASCRS and ESCRS

Corneal transplantation in eyes with keratoconus is known to have an excellent prognosis for graft survival. The favorable prognosis for penetrating keratoplasty in these eyes is in large part attributed to the lack of corneal vascularization or ocular inflammation in this disorder (Arentsen 1983). In some patients with keratoconus, and in patients with pellucid marginal degeneration, which is presumed to be a related disorder (Krachmer et al. 1984), severe stromal thinning extends into the corneal periphery. Penetrating keratoplasty with standard diameter recipient beds of 7.5–8.5 mm in these patients may result in graft-host tissue disparity, wound leaks, and high post-keratoplasty astigmatism. Corneal grafts employing a larger than standard diameter recipient bed allows more peripheral placement of the graft-host interface where the host cornea is less severely thinned. Placement of the graft in closer proximity to the limbal vasculature is, however, thought to increase the probability of allograft rejection reactions (Cherry et al. 1979). In this report, we present our experience with large diameter grafts for keratoconus and pellucid marginal degeneration.

PURPOSE: To evaluate the efficacy of transverse keratotomy followed by LASIK for patients with high amounts of naturally occurring astigmatism. METHODS: Thirteen eyes with naturally occurring astigmatism ranging from -3.75 to -6.50 diopters (D) underwent sequential transverse keratotomy (60° at 6 mm) and LASIK procedures. The effect of these two procedures on the amount of astigmatism was studied. RESULTS: Transverse keratotomy led to a 46% reduction in refractive cylinder from -5.50±0.80 D to -3.00±1.00 D. After LASIK, the initial refractive astigmatism was reduced by 90% to -0.50±0.50 D with a minimum follow-up of 6 months. CONCLUSIONS: The combined technique of transverse keratotomy followed by LASIK is an effective and accurate way to treat high amounts of naturally occurring astigmatism, allowing the size of the optical zone of the excimer laser ablation to be maximized. [J Refract Surg. 2007;23:209-211.]

Purpose: To evaluate the use of a picosecond neodymium:YLF (Nd:YLF) laser as a nonmechanical intrastromal microkeratome. Setting: Universita Cattolica del Sacro Cuore, Rome, Italy. Methods: An intrastromal spiral disc pattern of picosecond laser pulses was used to create a corneal flap for laser in situ keratomileusis (LASIK) in 14 partially sighted eyes. Results: Flaps with a 6.0 mm diameter and 180 to 200 urn depth were successfully created in most cases. The underlying stroma was treated with a Lambda Physik excimer laser using a 3.5 to 4.5 mm optical zone. Patients were divided into 3 groups for target corrections of 5.0, 10.0, and 15.0 diopters of myopia. Good corneal clarity and refractive undercorrection were recorded in each group 6 months postoperatively. The undercorrection was due in part to the limited optical zone of the laser's delivery system. Some flap decentration was noted. Conclusion: This pilot study indicates that the Nd:YLF picosecond laser may be clinically applied for creating corneal flaps for LASIK. Further refinements of the laser delivery system will include enlargement of the flap diameter and improvements in flap centration. The use of a femtosecond laser may expand the capabilities and precision of this technology.

BACKGROUND: We studied the histopathology of the stromal wound healing response in the cat cornea following intrastromal photorefractive keratectomy (IPRK) with the Nd: YLF picosecond laser. METHODS: Intrastromal PRK was performed in the anterior stroma of cat corneas with the Nd:YLF picosecond laser. The cats were sacrificed at predetermined intervals ranging from immediately to 6 months postoperatively. Effects of the laser treatment on the epithelium, Bowman's layer, stroma, and the endothelium were evaluated using light and scanning electron microscopy. No anti-inflammatory agents were used. RESULTS: Intrastromal PRK resulted in no perceptible damage to the corneal epithelium or Bowman's layer either acutely or at 6 months. The corneal stroma showed multiple cavitations immediately after intrastromal PRK, which collapsed over several hours, followed by thinning of the cornea over 2 weeks. At 1 month, the stromal collagen was abnormal with surrounding hyperceUularity. The endothelium showed no injury, acutely or at 6 months. No thermal effects on stromal collagen were observed at 6 months, and disruption of the lamellar pattern was not apparent after the cavitation bubbles were reabsorbed. CONCLUSION: Intrastromal PRK can effectively remove stromal tissue without acute damage to the adjacent lamellae, epithelium, or endothelium. There is a transient cellular wound healing response associated with a transient stromal collagen abnormality at 2 weeks to 1 month, which was not apparent 2 months after the procedure. [J Refract Surg. 1995;11:442-447.]

Preoperative evaluation and surgical planning for penetrating keratoplasty in patients with dense cornea) scars is often difficult because of poor visualization of the anterior segment. We performed ultrasound biomicroscopy (50-megahertz frequency, 50-micron resolution) on five eyes of five patients with dense corneal opacities of different etiologies to evaluate the anatomic relationships of the iris, lens, angle, and ciliary body. Corneal thickness, the presence or absence of iridocorneal adhesions, peripheral anterior synechiae, and cyclitic membranes, intraocular lens position, and relationships among intraocular structures could be evaluated in vivo. Ultrasound biomicroscopy is the optimal method of obtaining reliable, high-resolution images delineating anatomic relationships and pathology in the anterior segment. This information aids in surgical planning for penetrating keratoplasty and anterior segment reconstruction.

The authors conducted an open-label nonrandomized parallel trial to examine whether the preoperative application of povidone-iodine to the ocular surface reduces the incidence of endophthalmitis after intraocular surgery. During an 11-month period, topical 5% povidone-iodine was used to prepare the conjunctiva in 1 set of 5 operating rooms, while silver protein solution was used in another set of 5 rooms. In all cases, surgeons continued to use their customary prophylactic antibiotics. A significantly lower incidence of culture-positive endophthalmitis (P less than 0.03) was observed in the operating rooms using povidone-iodine (2 of 3489 or 0.06%) compared with those using silver protein solution (11 of 4594 or 0.24%). Use of topical povidone-iodine in over 3000 cases was not associated with any adverse reactions. In a majority of the observed cases of endophthalmitis, some form of intraoperative communication with the vitreous cavity existed.

The authors conducted a case-control study to identify risk factors for postoperative endophthalmitis. Fifty-four cases of patients who developed endophthalmitis after intraocular surgery at the New York Eye and Ear Infirmary during the period from January 1988 through October 1990 were identified. A control group of 228 patients was randomly selected from the 24,105 patients who underwent intraocular surgery during this same period. Logistic regression analysis identified significant independent risks associated with intraoperative communication with the vitreous cavity (risk ratio 13.7, P less than 0.001) and use of an intraocular lens with haptics made of polypropylene (risk ratio 4.5, P = 0.007). The study predicts that there would be approximately 700 fewer cases of postoperative endophthalmitis annually in the United States (approximately a 50% decrease in incidence) if intraocular lenses with haptics made of polymethyl-methacrylate, rather than polypropylene, were used exclusively.

The source of infecting bacteria is often unknown in postoperative endophthalmitis. Using techniques of molecular epidemiology, the authors demonstrate that an organism isolated from the vitreous was genetically indistinguishable from an isolate recovered from the patient's eyelid, conjunctiva, or nose in 14 (82%) of 17 cases of endophthalmitis. In two cases of Staphylococcus epidermidis endophthalmitis, after cataract surgery was performed by the same surgeon on the same day, genetic analysis demonstrated that the infecting organisms from the two patients' vitreous were distinct, and, furthermore, that in each case the external isolates were indistinguishable from the vitreous isolate. The results implicate the patients' external tissues as the source of the infecting organism in those cases of acute postoperative endophthalmitis studied. Therefore, attention should be directed toward the external tissues and their microbial flora in the prophylaxis and prevention of postoperative bacterial endophthalmitis.

The authors performed a case-control study of risk factors for suprachoroidal expulsive hemorrhage (SEH); the study involved 68 SEH cases at their institution from 1981 to 1986. The authors examined 113 variables in the study group and a procedure-matched control group of 217 patients randomly selected from the 35,459 patients who underwent intraocular surgery during this period, and subjected them to bivariate and conditional logistic regression analysis. The incidence of SEH was 0.19% overall, 0.16% for lens-related procedures, 0.15% for glaucoma surgery, 0.41% for retinal and vitreous procedures, and 0.56% for keratoplasty. Statistically significant risk factors for SEH in age-adjusted bivariate analyses included: glaucoma (P less than 0.0001), increased axial length (P less than 0.0001), elevated intraocular pressure (IOP) (P less than 0.0001), generalized atherosclerosis (P = 0.007), and elevated intraoperative pulse (P = 0.0001). Conditional logistic regression analysis with frequency matching on age identified significant independent risks associated with a history of glaucoma, elevated IOP, increased axial length, and intraoperative tachycardia. One of the models predicts a 752-fold increased theoretical relative risk of SEH for a patient with axial length greater than or equal to 25.8 mm, a history of glaucoma, preoperative IOP greater than 18 mmHg, and intraoperative pulse greater than or equal to 85 beats per minute. The visual outcome after SEH was best in cases of extracapsular cataract extraction (ECCE), compared with other procedures. Results suggest that attention to multiple preoperative and intraoperative ocular and systemic variables may allow identification and prophylaxis of patients at risk for SEH.

PURPOSE: To study the effect of punctal plug placement in patients undergoing refractive surgery for correction of poor vision. METHODS: A retrospective study was performed of 12 patients (21 eyes) who presented for initial refractive surgery or retreatment after LASIK or photorefractive keratectomy to improve visual acuity. Uncorrected visual acuity (UCVA) was documented in each eye. If tear normalization test was positive (indicating dry eye), silicone punctal plugs were placed in the lower lids of both eyes. Subjective patient UCVA and Snellen UCVA were assessed at 1 month. RESULTS: At 1 month, two eyes improved by three Snellen lines, nine eyes improved by two lines, seven eyes improved by one line, and three eyes remained unchanged. Uncorrected visual acuity was considered statistically significant (P CONCLUSIONS: Patients with low refractive errors note improvement in visual acuity after punctal plug placement. [J Refract Surg. 2007;23:467-471.]

Optic disc pit is an embryological malformation of the optic nerve that occurs in less than one in 10,000 people. It is 10%-15% bilateral, and 25% to 70% of patients develop a neurosensory macular detachment within the 2nd to 4th decade.We report a case of unilateral optic disc pit maculopathy 2 months after laser-assisted in situ keratomileusis (LASIK) revision.

Purpose To evaluate the effect of hyperopic refractive surgery on intraocular lens (IOL) power calculation, compare published methods of IOL power calculation after refractive surgery, evaluate the effect of prerefractive surgery refractive error on IOL deviation, and introduce a new alternative formula for IOL calculation in patients who have had refractive surgery for hyperopia. Design Retrospective noncomparative case series. Participants Twenty eyes from 13 patients who had undergone cataract surgery after previous hyperopic refractive surgery. Methods Seven different methods of IOL calculation were performed retrospectively: clinical history (IOL hisK ), clinical history method at spectacle plane (IOL hisKs ), vertex (IOL vertex ), back calculated (IOL BC ), calculation based on average keratometry (IOL avgK ), calculation based on steepest keratometry (IOL steepK ), and calculation based on the double K formula (IOL doubleK ). Each method's result was compared with an exact IOL (IOL exact ), which would have resulted in emmetropia. Each method was then compared with change in spherical equivalent induced by refractive surgery (SE h ). A paired t test was used to determine statistical significance. Main Outcome Measure Mean error in IOL power prediction for each method when compared to IOL exact . Results When evaluating different methods of IOL calculations, IOL vertex was the most accurate, with a mean deviation from emmetropia of 0.42±1.75 diopters (D), followed by IOL BC (+0.54±1.86 D), IOL hisK (+1.56±2.35 D), IOL hisKs (+1.57±2.35 D), IOL steepK (+1.59±2.25 D), IOL doubleK (+1.65±2.56 D), and IOL avgK (+2.24±2.46 D). There was no statistical difference between IOL vertex , IOL BC , and IOL exact . The power of IOL avgK would be inaccurate by 0.27 x +1.53, where x = SE h . Thus, most patients without the adjustment to IOL avgK would be left myopic. However, when IOL avgK is adjusted with this formula, there is no statistical difference to IOL exact . Conclusions For IOL power selection in previously hyperopic patients, a predictive formula based only on SE h and current average keratometry readings was not found to statistically differ from IOL exact . The IOL vertex and IOL BC , which also did not statistically differ from IOL exact , require prerefractive surgery keratometry readings that are often not available to the cataract surgeon.

Nocturnal lagophthalmos is the inability to close the eyelids during sleep. Lagophthalmos is associated with exposure keratopathy, poor sleep, and persistent exposure-related symptoms. There are a variety of causes of lagophthalmos, grouped as proptosis/eye exposure etiologies and palpebral insufficiency etiologies. Although obvious lagophthalmos is usually detected, it is sometimes difficult to recognize obscure lagophthalmos, due either to eyelash obstruction or overhang of the upper lid anterior and inferior to the most superior portion of the lower lid in a closed position. We present a novel classification system and illustrations of obvious and obscure lagophthalmos. A diagnosis can usually be made with a focused history and slit lamp examination. Treatment is multipronged and may include minor procedures or ocular surgery to correct the lid malposition; natural, topical or oral agents; and punctal plugs to manage ocular surface effects. Correct and timely diagnosis allows greater opportunity for relief of patient suffering and prevention of severe ocular surface pathology, as well as educated planning for future ocular surgical procedures.

We present a case of late traumatic flap dislocation 47 months after laser in situ keratomileusis (LASIK). This is the latest reported case of traumatic LASIK flap dislocation to date. The patient was examined 5 days after being struck in the face and found to have a flap dislocation. The flap was repositioned surgically, and postoperatively the patient had 20/20 visual acuity and no visual complaints.

Purpose To evaluate the ability of ultrasound biomicroscopy to monitor the repair of large Descemet's membrane detachments. Methods Intraoperative ultrasound biomicroscopy was performed in two patients who had undergone previous unsuccessful surgical repair of large Descemet's membrane detachments. Results Ultrasound biomicroscopy visualized and located Descemet's membrane detachment and verified proper suture placement and membrane repositioning. Conclusions Ultrasound biomicroscopy is a useful tool to guide surgical repair of Descemet's membrane detachments, particularly when hazy media prevent satisfactory visualization.

Purpose To evaluate the effect of refractive surgery on intraocular lens (IOL) power calculation, compare methods of IOL power calculation after refractive surgery, evaluate the effect of pre-refractive surgery refractive error on IOL deviation, review the literature on determining IOL power after refractive surgery, and introduce a formula for IOL calculation for use after refractive surgery for myopia. Setting Laser & Corneal Surgery Associates and Center for Ocular Tear Film Disorders, New York, New York, USA. Methods This retrospective noncomparative case series comprised 21 patients who had uneventful cataract extraction and IOL implantation after previous uneventful myopic refractive surgery. Six methods of IOL calculation were used: clinical history (IOL HisK ), clinical history at the spectacle plane (IOL HisKs ), vertex (IOL vertex ), back-calculated (IOL BC ), calculation based on average keratometry (IOL avgK ), and calculation based on flattest keratometry (IOL flatK ). Each method result was compared to an “exact” IOL (IOL exact ) that would have resulted in emmetropia and then compared to the pre-refractive surgery manifest refraction using linear regression. The paired t test was used to determine statistical significance. Results The IOL HisKs was the most accurate method for IOL calculations, with a mean deviation from emmetropia of −0.56 diopter ±1.59 (D), followed by the IOL BC (+1.06 ± 1.51 D), IOL vertex (+1.51 ± 1.95 D), IOL flatK (−1.72 ± 2.19 D), IOL HisK (−1.76 ± 1.76 D), and IOL avgK (−2.32 ± 2.36 D). There was no statistical difference between IOL HisKs and IOL exact in myopic eyes. The power of IOL flatK would be inaccurate by −(0.47 x + 0.85), where x is the pre-refractive surgery myopic SE (SEQ m ). Thus, without adjusting IOL flatK , most patients would be left hyperopic. However, when IOL flatK is adjusted with this formula, it would not be statistically different from IOL exact . Conclusions For IOL power selection in previously myopic patients, a predictive formula to calculate IOL power based only on the pre-refractive surgery SEQ m and current flattest keratometry readings was not statistically different from IOL exact . The IOL HisKs , which was also not statistically different from IOL exact , requires pre-refractive surgery keratometry readings that are often not available to the cataract surgeon.

* BACKGROUND AND OBJECTIVE: To determine the nature and chemical composition of the cavitation bubbles generated by intrastromal photorefractive keratectomy (IPRK) with the Neodymium: Yttrium Lithium Fluoride (Nd:YLF) picosecond laser. * MATERIALS AND METHODS: IPRK was performed on the corneas of three fresh human cadaver eyes with the Nd:YLF picosecond laser. High energy levels of 200 mJ/pulse to 300 mJ/pulse were used to produce the maximum amount of gas within the corneal stroma. The cavitation bubbles produced in the stroma were aspirated using a gas-tight syringe connected to a valve, and the specimens were analyzed with a mass spectrometer. * RESULTS: The experiment was performed on three different occasions using one cadaver eye in each experiment. The analysis consistently revealed a mixture of carbon dioxide, carbon monoxide, water vapor, oxygen, and nitrogen. Atmospheric control samples also revealed oxygen and nitrogen. No other components were detected. * CONCLUSION: The gaseous by-products of IPRK with the picosecond laser result from the simple breakdown of stromal tissue and contain no toxic or unexpected components. We found that these gaseous products are capable of rapid elimination by absorption or diffusion out of che intact cornea. [Ophthalmic Surg Lasers 1995;26:481-483.]

Epithelial ingrowth is a common complication of laser in situ keratomileusis (LASIK). The cause is thought to be postoperative invasion of surface epithelial cells under the flap. We present a case of advanced epithelial cystic ingrowth that caused a profound reduction in visual acuity 6 months after a second LASIK enhancement.

Purpose To elucidate risk factors, microbial culture results, and visual outcomes for infectious keratitis after photorefractive keratectomy (PRK). Design Multicenter, retrospective chart review, case report, and literature review. Methods The records of 12 patients with infectious keratitis after PRK were reviewed. Main outcome measures Causative organism, response to medical treatment, and visual outcome. Results Infectious keratitis developed in 13 eyes of 12 patients after PRK. Organisms cultured were Staphylococcus aureus (n = 5), including a bilateral case of methicillin-resistant Staphylococcus aureus ; Staphylococcus epidermidis (n = 4); Streptococcus pneumoniae (n = 3); and Streptococcus viridans (n = 1). Four patients manipulated their contact lenses, and 2 patients were exposed to nosocomial organisms while working in a hospital environment. Prophylactic antibiotics used were tobramycin (nine cases), polymyxin B-trimethoprim (three cases), and ciprofloxacin (one case). Final best spectacle-corrected visual acuity ranged from 20/20 to 20/100. Conclusions Infectious corneal ulceration is a serious potential complication of PRK. Gram-positive organisms are the most common pathogens. Antibiotic prophylaxis should be broad spectrum and should include gram-positive coverage.

Case report: Optic disc pit is an embryological malformation of the optic nerve that occurs in less than one in 10000 people. It is 10%–15% bilateral, and 25% to 70% of patients develop a neurosensory macular detachment within the 2nd to 4th decade. Comments: We report a case of unilateral optic disc pit maculopathy 2 months after laser-assisted in situ keratomileusis (LASIK) revision.

PURPOSE: To evaluate corneal morphology in vivo following intrastromal photorefractive keratectomy (D?RK) with the Nd:YLF picosecond laser, using the ultrasound biomicroscope. MATERIALS AND METHODS: Myopic intrastromal PRK was performed in the anterior stroma of cat corneas with the neodymium:yttrium lithium fluoride (Nd:YLF) picosecond laser. Periodic examination of the treated corneas up to 6 months postoperative was performed with high resolution ultrasound biomicroscopy. Corneal thickness, depth of the laser patterns from the corneal surface, alignment of the laser treatment, extent of stromal opacification until resolution, and contour of the corneal surface were measured with the ultrasound biomicroscope throughout follow up. RESULTS: The treated corneas were thickened on ultrasonic biomicroscopy measurement immediately after intrastromal PRK and revealed a densely echogenic shadow parallel to the corneal surface at the treatment site. There was increased stromal echogenicity denoting mild edema. The echoes decreased over time and appeared thinner at 2 months compared to the preoperative and immediate postoperative measurements. At 6-month follow up, the treated corneas were echolucent on ultrasonic biomicroscopy. CONCLUSION: The ultrasound biomicroscope might become a helpful tool in assessing accuracy of treatment parameters of intrastromal PRK as well as in monitoring the response of the cornea to treatment. [J Refract Surg. 1995;11:448-452.]

The problem of late bleb-related endophthalmitis is of great concern to glaucoma surgeons because of its increasing incidence related to the widespread use of adjunctive antifibrosis therapy. We therefore read with interest the article by Brown et al 1 because of the important nature of the problem. Unfortunately, our prior publication 2 on this topic must have eluded their literature search. The conclusions of the article by Brown et al mirrored ours. In our 1991 article 2 evaluating a series of 13 patients with late bleb-related endophthalmitis following trabeculectomy with fluorouracil, we reported a late infection rate of 3.0% for filtering surgery performed above the horizontal meridian and a rate of over 9.0% for surgery performed below the horizontal meridian. An intermittent positive Seidel test and thin-walled bleb were present in 62% of our cases presenting with an infection. All patients without vitreous involvement at the time of presentation had

A recent case-control study indicated that the insertion of an intraocular lens with polypropylene (Prolene) haptic materials was a significant risk factor for postoperative endophthalmitis (odds ratio = 4.5, P.01). In the present study, we used quantitative techniques to evaluate adherence of Staphylococcus epidermidis to two intraocular lens types--lenses with polypropylene haptic materials and all-polymethyl methacrylate optic and three-piece all-polymethyl methacrylate lenses--using a quantitative culture method, a radioisotope technique, and scanning electron microscopy. All three methods demonstrated approximately twice as many bacteria adherent to lenses with polypropylene haptic materials as to all-polymethyl methacrylate lenses. Scanning electron microscopy showed preferential bacterial adherence to the polypropylene haptic materials. These data provide a pathogenic mechanism to explain our epidemiologic findings of an increased risk of postoperative endophthalmitis associated with implantation of intraocular lenses with polypropylene haptic materials.

Background: The use of topical mitomycin (mitomycin-C) as a medical adjunct to pterygium and glaucoma surgery is increasing. Methods: The authors report on a series of 10 patients who experienced serious, vision-threatening complications associated with the use of this drug after pterygium surgery. Results: Complications included severe secondary glaucoma (4 patients), corneal edema (3 patients), corneal perforation (1 patient), corectopia (2 patients), iritis (8 patients), sudden onset mature cataract (2 patients), scleral calcification (1 patient) and incapacitating photophobia and pain (8 patients). Two patients required penetrating keratoplasties and a third required three lamellar keratoplasties. Another patient underwent four additional surgeries including a conjunctival Z-plasty, scleral patch grafting, and conjunctival autografting before his intractable pain and photophobia resolved 15 months after the original surgery. Because of these complications, 6 patients required a total of 20 return visits to the operating room after their original pterygium surgery. In 5 eyes, visual acuity remained at 20/200 or less. Three of the six patients with the most severe complications had concomitant chronic external diseases (rosacea [3 patients], ichthyosis [1 patient], keratitis sicca [1 patient]). Conclusion: The authors urge extreme caution in the use of mitomycin. If mitomycin is used, the lowest possible concentration should be applied for the shortest time period in an effort to avoid these complications. A prospective multicenter study of the ophthalmic use of this medication is needed.

• The effects of gas-permeable contact lens wear on the density and morphologic characteristics of corneal endothelial cells were prospectively studied by wide-field specular microscopy in 18 eyes that had undergone keratoplasty at least 14 months previously. Daily-wear rigid gas-permeable lenses were fitted to allow as much movement and tear exchange as possible. There was no evidence of morphologic instability of the endothelial cells during the course of the study, with a mean duration of lens wear of 9.8 months. Although there is concern over adverse effects associated with polymethylmethacrylate contact lens wear, this study suggests that the endothelium of a corneal transplant tolerates rigid gas-permeable lens wear without adverse effect during a limited period of follow-up.

The incidence of late-onset bleb-related endophthalmitis was evaluated retrospectively in 229 consecutive trabeculectomies performed with adjunctive 5-fluorouracil (5-FU) therapy. Mean follow-up was 23.7 +/- 16.3 months (range, 3 to 60 months). Thirteen eyes (5.7%) of 11 patients developed bleb-related endophthalmitis an average of 25.9 +/- 17.4 months (range, 5 to 58 months) after surgery. Infection occurred in 9 of 96 (9.4%) procedures performed from below and in 4 of 133 (3.0%) procedures performed superiorly (P = 0.05, Fisher's exact test). The relative risk of bleb-related endophthalmitis in trabeculectomy from below versus above is 4.0 after adjustment for age and sex (95% confidence interval = 1.1, 14.8). Trabeculectomy with adjunctive 5-FU performed from below carries an increased risk of late bleb-related infection. The incidence of late bleb-related endophthalmitis after 5-FU trabeculectomy appears to be higher than that for trabeculectomy without adjunctive 5-FU injections.

Objective: To evaluate the refractive effects of myopic intrastromal photorefractive keratectomy (IPRK) with the neodymium-yttrium lithium fluoride (Nd-YLF) picosecond laser. Methods: A 1053-nm Nd-YLF picosecond laser was used to produce myopic IPRK in cat corneas at threshold energy densities. Preoperative corneal topography and ultrasonic pachymetry were performed followed by IPRK in one eye each of 21 cats. No anti-inflammatory medications were administered. Postoperative corneal topography, ultrasonic pachymetry, and slit-lamp examination were performed at scheduled intervals. Results: An average topographic flattening of 11.4 di-opters and pachymetric thinning of 50 μm at the center of the treatment zone were observed by 6 weeks following treatment. The average diameter of the zone of flattening was 5.1 mm at 6 weeks and 6.0 mm at 12 weeks postoperatively. At 6 months postoperatively, the average central corneal power was unchanged, while the average central thickness had returned to the preoperative value. A mild subepithelial haze was detected at 1 month following IPRK, which was barely perceptible at the second through sixth months. Regression of the topographic effects of PRK was not observed. Conclusion: Intrastromal PRK with the Nd-YLF picosecond laser produces central flattening of the cat cornea with barely perceptible stromal haze and no regression of topographic effect after 6 months in the absence of treatment with anti-inflammatory agents.

In Reply. —We appreciate Dr Lieberman's comments regarding the treatment of exposed glaucoma setons. This difficult problem developed more frequently prior to the use of fullthickness scleral patch grafts to cover glaucoma implants, but still occurs on occasion. The use of scleral patch grafts during the surgical revision of exposed glaucoma implants appears to improve the likelihood of success, compared with conjunctivoplasty alone (with or without repositioning of the tube). We look forward to reports of the use of autologous fascial grafts as an alternative technique for this purpose. If this alternative proves superior, it may become preferable to the use of scleral patch grafts at the time of initial surgery, particularly in this era of concern about blood-borne diseases.

Seton implantation has become increasingly useful in the surgical management of glaucoma. 1 Complications of this surgery include those common to any filtration surgery, such as cataract, choroidal effusion or hemorrhage, early or late endophthalmitis, retinal detachment, or Tenon cyst and others unique to the presence of an implanted foreign body, such as extrusion or late erosion through the overlying sclera and/or conjunctiva and Tenon's fascia. 1 A single case of early postoperative endophthalmitis has also been reported. 2 We treated two patients for late endophthalmitis following external erosion of the implant through the conjunctiva. To our knowledge, this complication has not been previously reported. Report of Cases. —Case 1. —A 65-year-old woman with neovascular glaucoma following an ischemic central retinal vein occlusion underwent implantation of a shorttailed Krupin-Denver valve beneath a partial-thickness scleral flap in her right eye in 1984. Preoperative visual acuity was hand motions. During the

We reviewed the records of all patients with pseudophakic bullous keratopathy (271 eyes, 251 patients) seen during a six-month period to determine predisposing factors, associated problems, current management, and visual outcome. Pseudophakic bullous keratopathy was associated most frequently with anterior chamber intraocular lenses in general (155 of 271), and with Leiske style lenses in particular (100 of 271). It was associated with a visual acuity of 20/200 or less in 206 eyes and a visual acuity of counting fingers or less in 129 of the eyes at the initial examination. Penetrating keratoplasties had been performed in 189 of the eyes. After penetrating keratoplasty, 108 of 189 of the eyes had a visual acuity of 20/200 or less (mean follow-up, 15 months). Visual acuity improved with longer follow-up, and among patients with a minimum follow-up of two years, 23 of 36 eyes had a visual acuity of 20/100 or better. Most grafts were clear (145 of 189). Pseudophakic bullous keratopathy was associated with marked visual loss, which was permanent despite clear grafts in 29 of 92 eyes followed-up for one year or longer.

Management of the intraocular lens (IOL) at the time of penetrating keratoplasty (PK) for pseudophakic bullous keratopathy has been based on lens-related factors and coexisting anterior segment abnormalities. The authors reviewed the results of PK for 102 cases of pseudophakic bullous keratopathy (43 anterior chamber, 50 iris-supported, and 9 posterior chamber) with respect to: (1) the type of IOL, (2) coexisting abnormalities, and (3) management of the IOL at surgery. Graft failure after 2 years of follow-up was: (1) retained iris-supported IOLs, 9%; (2) retained anterior chamber IOLs, 60%; (3) retained posterior chamber intraocular lenses (PC IOL), 0%; (4) removed IOLs, 9%; and (5) exchanged IOLs, 20%. After 5 years of follow-up, 13 of 13 PKs with retained closed-loop anterior chamber IOLs had failed. Visual results were best in eyes with retained iris-supported, rigid anterior chamber or PC IOLs and when the IOL was removed without replacement. The authors recommend that closed-loop anterior chamber lenses and unstable lenses of any type be removed or exchanged and that well-fixated PC IOLs and iris-clip IOLs be retained at the time of PK for pseudophakic bullous keratopathy.

A calmodulin-binding protein is present in extracts of the macrophage-like mouse cell line J774 and in extracts of thioglycollate-stimulated mouse peritoneal macrophages; it is deficient in variants of J774 resistant to trifluoperazine and in resident peritoneal macrophages. The calmodulin-binding protein [CaMBP (J7)0.5] was purified from J774 and resolved from endogenous cyclic nucleotide phosphodiesterase and protein kinase activities. The protein has an apparent native Mr of 125,000-150,000 and binds calmodulin in a calcium-dependent manner with a Kd of 20 nM. It inhibits the ability of calmodulin to activate phosphodiesterase. Its sedimentation constant in glycerol gradients containing calmodulin was dependent upon the relative concentrations of calmodulin and the calmodulin-binding protein.