Search

We describe what are to our knowledge the first in vivo measurements of human retinal structure with optical coherence tomography. These images represent the highest depth resolution in vivo retinal images to date. The tomographic system, image-processing techniques, and examples of high-resolution tomographs and their clinical relevance are discussed.

• Several fluids of different viscosity were used to mask deeper tissues while exposing protruding irregularities during therapeutic keratectomy of an irregular anterior corneal surface with the 193-nm argon fluoride excimer laser. A model of an irregular anterior corneal surface was developed in deepithelialized calf eyes using grade 8-0 sandpaper. Therapeutic keratectomy was then performed on 28 eyes at a fluence of 180 mJ/cm 2 , a repetition rate of 10 Hz, and 500 pulses per eye. Solutions of 0.3% hydroxypropylmethylcellulose 2910 and a 0.1% dextran 70 solution, 1% carboxymethylcellulose sodium solution, or 0.9% saline solution were applied to the corneal surface of 21 eyes. Seven control eyes underwent ablation without the addition of fluid. Scanning electron microscopy demonstrated that corneas treated with dextran 70 had the least surface irregularity, and those treated with carboxymethylcellulose or saline solution had intermediate surface irregularity. Corneas that were ablated without additional fluid had the greatest surface irregularity. The application of a moderately viscous solution during therapeutic excimer laser keratectomy enhances the smoothing effect of surface ablation.

• Five patients presented with vision-threatening retinal tumors and systemic signs of neurofibromatosis, including neurofibromatosis type 1 (four patients) and familial cafe-au-lait spots (one patient). These tumors included large retinal astrocytic hamartomas, multiple retinal capillary hemangiomas, and combined hamartomas of the retina and retinal pigment epithelium, which resulted in rubeotic glaucoma, vitreous hemorrhage, and retinal detachment. Surgical therapy included retinal cryopexy, xenon and argon photocoagulation, scleral buckling, and pars plana vitrectomy with excisional retinal biopsy. Retinal tumors may result in marked visual loss in patients with neurofibromatosis, and vitreoretinal surgery may restore useful vision in some of these patients.

We performed anterior keratectomies on six monkey eyes, four by excimer laser large-area ablation at 193 nm and two by mechanical keratectomy. Immunofluorescence was used to study the wound healing response histopathologically. The distribution of fibrinogen, fibronectin, laminin, collagen types III, IV, and VI, and keratan sulfate was determined at postoperative intervals of 24 hours, 6 days, and 1 month. At 24 hours, fibrinogen and fibronectin coated the ablated surface, but corneal epithelial cells had not yet migrated over the wound. By 6 days and persisting at 1 month, an epithelial ingrowth of seven to 10 layers, mild stromal hypercellularity, and new collagen formation were present in the repair region. At 1 month, fibrinogen, fibronectin, laminin, and type III collagen were strongly detected in the repair region. Type VI collagen was present in both normal and healed corneal stroma at all intervals, and type IV collagen was present in Descemet's membrane only. Sulfated keratan sulfate was absent from the newly synthesized collagen stroma at all intervals. Slit-lamp photographs demonstrated corneal haze in the ablation zone in all cases at 24 hours, persisting for 1 month. The fluorescence patterns produced by excimer laser ablation and mechanical keratectomy were qualitatively identical.

• In nine cynomolgus monkeys, trabeculopuncture was performed with a Q-switched neodymium-YAG laser, using a pulse energy of 5 to 7 millijoules and an exposure time of 14 nanoseconds. A penetration into Schlemm's canal was successfully achieved with two to four pulses; this penetration was accompanied by intraocular pressure (IOP) reduction and blood reflux into the anterior chamber. However, after eight days, IOP returned to baseline level, while white tissue was observed gonioscopically to fill in the puncture sites. Histologically, one hour after laser treatment, a blasting effect on the trabecular meshwork was observed with no signs of necrosis. Ater eight days, a hypertrophic scar formed, with the corneal endothelium extending over the scarred surface. At eight weeks and at six months after laser treatment, further shrinkage of the scar and the formation of a membrane over it was evident. Attempts to control scar formation by preventing blood reflux or injecting fluorouracil subconjunctivally for two weeks were unsuccessful. Scar formation at the trabecular puncture site severely limits the applicability of this potentially simple glaucoma treatment.

The pulsed ultraviolet excimer laser has been used to produce tissue ablation with a high degree of precision and with minimal thermal damage to adjacent structures. In comparative studies of excimer laser ablation of the cornea and crystalline lens using 193 nm and 248 nm radiation, threshold fluence for corneal and lens ablation was higher at 248 nm than at 193 nm. Ablation of corneal stroma at 193 nm produced the most precise cuts. When examined by transmission electron microscopy, a narrow zone of damaged tissue (0.1 to 0.3 micron) was seen immediately adjacent to the tissue removed by the laser. Ablation with 248 nm radiation produced incisions with ragged edges and with a wider and more severe zone of damage in adjacent stroma. Ultraviolet spectral transmission studies of the corneal stroma showed that absorption is 10 times greater at 193 nm than at 248 nm. The excimer laser was effective in producing well controlled ablation of the crystalline lens in vitro, with effects parallel to those seen in the cornea.

We report the first study of laser-tissue interaction in the femtosecond time regime. Retinal damage thresholds and mechanisms produced by exposure to high-intensity femtosecond laser pulses were investigated in chinchilla grey rabbits. Exposures were performed using single laser pulses of 80 fs duration at 625 nm. ED 50 injury thresholds of 0.75 and 4.5 μJ were measured using fluorescein angiographic and ophthalmoscopic visibility criteria evaluating 204 laser exposures. Ultrastructural studies including light and electron microscopy were performed on selected lesions. Results suggest that the primary energy deposition in the retina occurs in melanin, However, in contrast to laser injuries produced by longer pulses, exposures of more than 100 × threshold in the 50-100 \mu J range did not produce significantly more severe lesions or hemorrhage. This suggests the presence of a nonlinear damage limiting mechanics in tissue exposed to femtosecond laser pulses.

SummaryAIU (5-iodo-5′-amino-2′,5′-dideoxyuridine, AIdUrd) has been shown to be as effective as IdUrd in the treatment of experimental herpes simplex keratitis in rabbits. AIU's striking lack of cellular or systemic toxicity or teratogenicity and its specific inhibition of viral metabolism are discussed.The authors acknowledge the valuable technical assistance of Mr. Alfred S. Fiore and Mr. Ronald Callahan (Departments of Pharmacy and Nuclear Medicine, Massachusetts General Hospital). Mrs. Brigitte A. Prusoff performed the statistical analysis.

In five patients with choroidal melanoma occurring among present or former workers of the duPont Belle, West Virginia, plant the involved eye was enucleated and histopathologic confirmation of the diagnosis was made. This represents a statistically significantly greater than expected occurrence of choroidal melanomas in the white male study population.

In three aphakic eyes and two eyes with intraocular lens implants (five patients, four women and one man, ranging in age from 65 to 76 years) persistent shallow or flat anterior chamber was observed despite multiple patent laser or surgical iridectomies. In each case direct application of the neodymium-YAG laser (3 to 11 mJ) to the anterior hyaloid face resulted in immediate deepening of the anterior chamber. This deepening was sustained in four of the cases. These results confirm previous observations suggesting that the anterior hyaloid can be the locus of abnormality in aphakic malignant (ciliovitreal block) glaucoma. Neodymium-YAG "hyaloidotomy" may be better than penetrating surgery in such cases.

Because microplasma formation may provide an energy-absorbing shield that protects the retina from inadvertent injury during neodymium-YAG laser surgery, we studied plasma formation and shielding by three ophthalmic neodymium-YAG lasers (the Q-switched American Medical Optics YAG-100, the mode-locked Meditec OPL-3, and the Q-switched LASAG Sirius Microruptor 2) with three model targets (physiologic saline, 1% sodium hyaluronate, and a cellophane membrane). Plasma formation produced a linear reduction in the transmission of light energy along the beam path in a qualitatively similar manner for all three lasers but there were quantitative differences. Plasma shielding was similar in both saline and sodium hyaluronate; enhancement of the shield effect occurred only with the cellophane membrane target. Operating the lasers at energy levels far above threshold did not reduce total light transmission significantly. Clinical use should be guided by the principle of employing the minimum energy necessary to cut the target tissue.

The effects of picosecond laser-induced optical breakdown on tissue were investigated using high-intensity 40 ps Nd:YAG laser pulses at 1.06 microns. Tissue damage was evaluated using the corneal endothelium in vitro as a model system. Systematic studies were performed to determine the scaling of the tissue damage and damage range with pulse energy. For suprathreshold lesions, the radius of the damage zone varies as the cube root of the pulse energy, in agreement with simple physical scaling laws. A minimum damage range of less than 100 microns was observed for pulse energies of 8 muJ. Damage morphology was investigated by scanning electron microscopy. Three different damage patterns were observed; cell damage, cell removal, and rupture of Descemet's membrane. Different irradiation geometries were used to study damage mediated by either the shock wave or the cavitation bubble. Comparative studies using 10 ns pulses demonstrated that picosecond pulses yielded a significant reduction in collateral tissue damage.

• Laser endophotocoagulation is an important technique in vitreoretinal surgery. We performed successful retinal endophotocoagulation in the eyes of Dutch-belted rabbits, using high-power phased-array semiconductor lasers, emitting at 808 and 817 nm. The laser itself measured 25 × 30 × 21 mm, was air cooled, and was portable. At a treatment power of 100 mW, uniformly white photocoagulation lesions were seen at exposure durations of 0.2 to 1.0 s. Lesions were similar in appearance to argon laser photocoagulation lesions, as determined by ophthalmoscopy and fluorescein angiography. Thin-section histologic examination of acute lesions revealed injury localized to the outer retina; chorioretinal scar formation was noted ten days after photocoagulation. To our knowledge, this study is the first in which therapeutically useful lesions were produced using a diode laser and demonstrates the feasibility of using these highly efficient and compact laser sources for ophthalmic photocoagulation.

Le laser YAG est largement utilise pour pratiquer des capsulotomies posterieures et peut etre un instrument majeur dans le traitement de complications postoperatoires telles qu'un blocage pupillaire un glaucome malin une incarceration du vitre dans la plaie operatoire et pour lyser des synechies

Q -switched and mode-locked neodymium: YAG laser pulses can be used to produce optical breakdown inside the eye, permitting surgical disruption of transparent or pigmented ocular tissues. The physical processes responsible for the initiation, propagation, and control of this important and novel class of laser tissue interactions are reviewed.

Principles of laser-tissue interactions in the eye are reviewed. Corneal structure and function are summarized, with particular regard for features related to laser treatment. A summary of argon and carbon dioxide laser techniques in the cornea is presented, followed by a review of studies on corneal response to ultraviolet radiation. A detailed description is then given of the characteristics of excimer laser tissue ablation. Potential applications of this process in corneal and keratorefractive surgery are reviewed.

Tissue absorption lengths for infrared radiation at 2.8 to 3.1 μm are very short due to strong absorption by water. Corneal ablation using pulsed lasers at these wavelengths can potentially produce incisions similar in quality to cuts produced by excimer lasers at 193 nm. The authors have used 8-ns pulses at 2.80 and 2.92 ,μm, generated by a Raman-shifted neodymium:YAG (Nd:YAG) laser, to make slit-like incisions in bovine and human corneas. At 2.8 μm, etch depth per pulse increases sigmoidally from 0.15 μm at 390 mJ/cm 2 to 3.8 μm at 2200 mJ/cm 2 . No ablation occurs at fluences below 250 mJ/cm 2 . Light and transmission electron microscopy show smooth-walled incisions bordered by a thermally damaged region that varies in width from 1.5 μm at 600 mJ/cm 2 to 10 μm at 2200 mJ/cm 2 . The small amount of tissue damage produced at low fluences suggests that infrared ablation may be useful in keratorefractive surgery.

We reviewed 65 cases of uveal melanoma from the Shanghai Eye, Ear, Nose, and Throat Hospital between 1956 and 1979. These 65 cases occurred at a rate of 4.5 cases per 10,000 inpatients on the ophthalmology service. Uveal melanoma is more frequently encountered in China than previous reports have suggested. In China, as in the United States, uveal melanoma is the most frequently occurring primary intraocular neoplasm in adults. We observed a strikingly younger age distribution of our cases; almost 20 percent of cases in our series involved patients between the ages of 19 and 30. The largest number of cases was seen in the fifth decade. However, only 5 cases (8 percent) were seen in the sixth decade. Fundus lesions, which were observed to stimulate choroidal melanoma, are similar to those encountered in the United States. One contrast was the importance of inflammatory lesions in the differential diagnosis of choroidal melanoma. Management of cases was surgical in all instances. A lower percentage of spindle cell tumors and a higher percentage of epitheloid tumors were seen than in most Western series.

We have used laser-based high-speed photography to investigate excimer laser ablation of the cornea. Photographs of the ablation plume were obtained 500 ns to 150 microseconds after incidence of a 193- or 248-nm excimer laser pulse on the surface of the cornea. Ejection of material from the cornea begins on a time scale of nanoseconds and continues for 5 to 15 microseconds following the excimer pulse. At 193 nm the ablation plume resembles a burst of smoke, and individual particles are too small to be optically resolved with our apparatus. At 248 nm the plume resembles a spray of larger, discrete droplets. Material is ejected from the cornea at supersonic velocity but decelerates rapidly; the velocity for the first 500 ns following the excimer pulse averages 400 m/s at 193 nm. Plume size and velocity increase with increasing fluence.

A three-year retrospective study of 36 cases of infectious endophthalmitis seen at a large referral eye center between 1977 and 1980 was conducted. The criterion for infectious endophthalmitis was the culture of microorganisms from aqueous or vitreous on at least two media. The most frequent pathogen was Staphylococcus epidermis; it was isolated from 18 (50%) of the cases. In cases of infectious endophthalmitis following recent cataract extraction, S. epidermidis was isolated from 10 to 17 eyes (58.8%). Complete loss of visual function occurred in 16 of the 36 eyes (44.4%); a visual acuity of 20/400 or better as recorded in 15 eyes (41.6%) and 20/100 or better in eight (22.2%). Fifty percent of the cases were treated with vitrectomy and intraocular antibiotics. Poor visual outcome was associated with gram-negative organisms or delay of vitrectomy more than 24 hours after the initial diagnosis. In cases of postoperative S. epidermidis endophthalmitis, the most favorable visual outcomes were associated with use of intraocular antibiotics and vitrectomy; 80% of cases so treated had a final visual acuity of 20/400 or better and 60% had a visual acuity of 20/100 or better.

The authors used high peak power nanosecond (Q-switched) and picosecond (mode-locked) pulses from the neodymium-YAG laser to perform experimental anterior and posterior capsulotomy in rabbits. The morphology of laser anterior capsulotomy was studied using scanning electron microscopy. Ultrastructural studies revealed no evidence of morphologic abnormality in the corneal endothelium in eyes in which laser capsulotomy had been performed. The critical factors for the prevention of inadvertent retinal injury during laser surgery in the anterior segment of the eye were identified as pulse energy and cone angle of incident laser radiation. Using wide angle fundus photography and fluorescein angiography, intentional retinal injury during laser surgery of the lens was experimentally documented when retinal radiant energy exposure exceeded injury threshold.

Sympathetic ophthalmia isa specific bilateral granulomatous inflammation of the uvea usually following surgical or accidental penetrating trauma to the globe. While generally considered rare, its true incidence is difficult to ascertain. One recent report noted an incidence of approximately two cases per 1,000 accidental perforations, and approximately one case per 10,000 intraocular surgical procedures. 1 Another recent clinical review of cases of sympathetic ophthalmia at one center over the past 20 years showed a decrease in the number of such cases following purely accidental or purely surgical injury, and an increase in the number of cases in which accidental injury was followed by surgical intervention in addition to primary repair. 2 Five cases of sympathetic ophthalmia following trauma and vitrectomy have been reported.3 It has been suggested by some that as more attempts at secondary reconstructive surgery (ie, vitrectomy) in severely traumatized eyes are made, a higher incidence of sympathetic uveitis may be expected. 2 However, it is also possible that a single primary or early secondary repair, including vitrectomy or len sectomy if indicated, may be less likely to incite sympathetic ophthalmia than mUltiple secondary procedures. The importance of early removal of lens material after trauma in the prevention of phacoanaphylaxis (phacogenic uveitis) has been stressed. 4 This report presents an additional case of sympathetic ophthalmia following scleral buckling, vitrectomy, and cataract extraction.

The Q-switched and mode-locked Nd:YAG lasers rapidly entered the ophthalmic surgical armamentarium as the tool of choice for discission of the posterior capsule.1–3 The large shift in the past decade from intracapsular to extracapsular surgery generated a widespread need for safe and effective techniques to manage both intact posterior capsules that opacify postoperatively and visually significant capsular fragments that remain after primary surgical capsular discission. The Nd:YAG laser also has proven to be a major tool in the management of postoperative complications, such as pupillary block and malignant glaucoma, vitreous incarceration in the wound, synechiae formation, and residual anterior capsular fragments.

The efficiency of cutting by single pulses and bursts of two, four, and eight pulses from a Q-switched Nd:YAG laser was determined in a model of a heavy membrane and a loosely floating target. The burst modes cut the targets somewhat more quickly than single shots, but required a marked increase in total energy delivered. Anterior movement of the breakdown zone and posterior displacement of the target explain the energy inefficiency of burst-mode photodisruption.

Transscleral photocoagulation of the ciliary body was achieved in pigmented rabbits using a sapphire probe delivery system coupled to a commercial surgical continuous-wave Nd:YAG laser. This contact technique was found to be effective in reducing intraocular pressure (IOP); greater treatment energies were associated with a more prolonged reduction in IOP, and also correlated with a greater degree of histologic damage to the ciliary body. Treatment energies of 0.8-1.0 Joules produced substantial disruption of the ciliary body. This technique is easy to learn and offers ease in control and placement of the coagulation spots.

We used a pulsed erbium-YAG laser emitting in the midinfrared region (2.94 microns) to cut experimental vitreous membranes in rabbits via an intraocular fiberoptic delivery system. Thirty-four membranes were cut at distances of 500 to 3600 microns from the retina. All 34 of the membranes treated were effectively cut. Sixteen cases had no evidence of retinal injury, including one in which the membrane was only 800 microns from the retina. Retinal injuries in the remaining cases consisted of small (less than 300 microns) retinal burns and hemorrhages. In 94% of the cases with retinal injury, the fiberoptic was within 2000 microns of the retina. We conclude that a pulsed erbium-YAG laser allows near tractionless cutting of vitreous membranes and may have potential for clinical use if further studies show it to be efficacious and safe near the retina.

Excimer laser radiation at 193 nm and 248 nm was used to create linear etch perforations of enucleated calf corneas. The etch depth per pulse was determined for various exposures, and specimens were examined by light and transmission electron microscopy. Compared to 248 nm, excimer laser ablation at 193 nm was found to have a lower threshold for onset of ablation, less increase in etch depth per pulse at increasing fluences, and less structural alteration in adjacent cornea. For 193 nm, structural alterations were minimal, confined to an area less than 0.3 micron wide, and did not increase with increasing fluence. These studies suggest that clinical strategies for excimer laser refractive surgery will employ the 193-nm wavelength, with fluence chosen depending on surgical strategy. Ablation exposures above 600 mJ/cm2 at 193 nm may give the most repeatable etch depth.

• Choroidal neovascularization in rat eyes was induced by krypton laser photocoagulation. Lesions were studied weekly by ophthalmoscopy, fundus photography, and fluorescein angiography. Morphologic correlation was provided by serial sectioning of lesions for light and transmission electron microscopy. In addition, vascular casts were prepared for scanning electron microscopy. Choroidal neovascularization occurred in 25 (60%) of 42 lesions, as evidenced by growth of capillaries through breaks in Bruch's membrane. In addition, 24 (28%) of 86 lesions studied by fluorescein angiography demonstrated leakage. This study provides the most complete angiographic, histologic, and ultrastructural documentation of experimental choroidal neovascularization in the rat. This model may be useful for in vivo studies of choroidal angiogenesis and its modulation via drug therapy.

Four members of one family had craniometaphyseal dysplasia. Two of the four had severe optic atrophy with profound loss of vision as a complication of this disorder. Optic nerve decompression attempted in one patient may have caused a reduction in the vision of that eye. Eight years later this patient underwent craniofacial surgery uneventfully for contouring of her facial and cranial bones, but osteotomies and intracranial surgery were specifically avoided because of bony over-growth in the foramen magnum region.

We produced corneal excisions with nanosecond (ns)-, picosecond-, and femtosecond (fs)-pulsed lasers at visible wavelengths. The threshold energy for ablation was proportional to the square root of the pulse duration and varied from 2.5 microjoules (microJ) at 100 fs to 500 microJ at 8 ns. Excisions made with picosecond and femtosecond lasers was ultrastructurally superior to those made with nanosecond lasers and, at pulse energies near threshold, showed almost as little tissue damage as excisions made with excimer lasers at 193 nm. We conclude that ultrashort-pulsed lasers at visible and near-infrared wavelengths are a possible alternative to excimer lasers for corneal surgery and might have advantages over conventional ophthalmic neodymium-YAG lasers for some intraocular applications.

• Ablation of the bovine crystalline lens was studied using radiation from an excimer laser at four ultraviolet wave lengths as follows: 193 nm (argon fluoride), 248 nm (krypton fluoride), 308 nm (xenon chloride), and 351 nm (xenon fluoride). The ablation process was quantitated by measuring mass ablated with an electronic balance, and characterized by examining ablation craters with scanning electron microscopy. The highest ablation rate was observed at 248 nm with lower rates at 193 and 308 nm. No ablation was observed at 351 nm. Scanning electron microscopy revealed the smoothest craters at 193 nm while at 248 nm there was vacuolization in the crater walls and greater disruption of surrounding tissue. The craters made at 308 nm did not have as smooth a contour as the 193-nm lesions. The spectral absorbance of the bovine lens was calculated at the wavelengths used for ablation and correlated with ablation rates and thresholds. High peak-power, pulsed ultraviolet laser radiation may have a role in surgical removal of the lens.

A Nd:YAG laser developed for ophthalmic surgery was studied for safety and efficacy in secondary discission of the posterior capsule in aphakic and pseudophakic subjects. The study involves 6,800 subjects, 526 of whom had completed the six-month postoperative course by the time the data base was closed for analysis. Of the 526 subjects who were treated with the laser, 87.8% had improved vision, with 82.9% achieving a visual acuity of 20/40 or better. This result compares favorably with results for the surgically treated population in which only 68.4% experienced improved vision, with 80.2% achieving a visual acuity of 20/40 or better. Approximately four times more surgically treated subjects than laser-treated subjects experienced diminished vision (14.8%). Cumulative complication rates in the laser-treated population were very low (CME 2.3%, secondary glaucoma 3.6%, retinal detachment 0.4%, overall rate 4.8%). Persistent complications (present at the six-month postoperative period) were present at an overall incidence of 2.3%, comprised primarily of CME, 0.2%, retinal detachment, 0.2%, and secondary glaucoma, 0.8%. Only 5.7% of subjects experienced an intraocular pressure (IOP) rise to 30 mm Hg or greater. Return to the preoperative IOP level occurred in 89% of subjects in the first 24 hours to one week. Predictors of IOP rise to 30 mm Hg or greater were determined to be preoperative glaucoma and/or preoperative IOP of greater than 20 mm Hg.

• Iridotomies were performed on pigmented rabbits with a Q-switched ophthalmic neodymium-YAG (Nd-YAG) laser and an argon laser. Because short-pulsed Nd-YAG lasers are effective in performing capsulotomies of the crystalline lens, injury to the underlying lens was evaluated by slit-lamp biomicroscopy at various intervals following the iridotomy, and then lenses were examined in vitro with the use of procion yellow, an extracellular dye. Patent iridotomies were produced with one to two pulse applications of the Nd-YAG laser. Focal areas of pigment deposition on the lens capsule and focal lens capsule opacities underlying the iridotomy site were observed, but no inadvertent capsulotomies occurred. Lens injury could be minimized through optimal focusing and energy selection. Minimal hemorrhage occurred with Nd-YAG laser iridotomy; prior treatment with the argon laser was not necessary to achieve hemostasis.

The high powered, short pulsed output of the excimer laser has been proposed for use is producing spatially confined tissue, ablation. In vitro studies of ablation of corneal tissue using 193 nm have been previously reported (Trokel, Srinivasan, Braren, 1983). The excimer laser may be useful in producing incisions in the cornea which alter the topography, thereby modifying the optical power of the cornea. The laser may therefore be applied therapeutically to the correction of myopia and astigmatism (that is, in refractive surgery of the eye).

• Ophthalmia nodosa is the nodular granulomatous inflammatory response of ocular tissue to caterpillar hairs. We experimentally simulated this condition by surgically implanting gypsy moth hairs in the rabbit cornea. We were not, however, able to produce ophthalmia nodosa solely by placing cilia in the rabbit culde-sac. The experimentally induced inflammation closely resembled human ophthalmia nodosa in both its clinical and histopathologic features.

Intraocular pressures (IOP) and tonographic outflow facilities were measured following neodymium (Nd): YAG laser posterior capsulotomy in 13 pseudophakic and 8 aphakic eyes. Mean intraocular pressure (IOP) peaked by three hours with a mean increase of 13 mmHg, remained elevated by 5 mmHg at 24 hours but returned to baseline by one week. Fourteen eyes (67%) had greater than or equal to 10 mmHg elevation and eight (38%) had greater than or equal to 40 mmHg maximum IOP. All the patients who eventually demonstrated a greater than or equal to 10 mmHg elevation within six hours of the capsulotomy initially had an IOP elevation greater than or equal to 5 mmHg at one hour. The mean outflow facility was reduced from 0.18 microl/min/mmHg before capsulotomy to 0.08 microl/min/mmHg (55%, P less than 0.0001) at four hours and was still decreased at 0.13 microl/min/mmHg (27%, P less than 0.05) at one week. Seventy-five percent of aphakic and 15% of pseudophakic patients had maximum IOP greater than or equal to 40 mmHg (P less than 0.01). Measurements should be performed one hour postlaser in all patients for IOP and three to four hours in aphakic patients, glaucomatous patients, patients receiving greater than or equal to 200 mjoules total laser energy, and patients with greater than or equal to 5 mmHg elevation at one hour in order to detect and treat significant IOP elevations.