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Purpose: To report on the occurrence of corneal guttae after Descemet membrane endothelial keratoplasty (DMEK) in eyes operated on for Fuchs endothelial corneal dystrophy (FECD)., Material and Methods: Case series of 10 eyes of 10 patients operated on for FECD at a tertiary referral center between 2008 and 2019. Average patient age was 61±12 years and 3 patients were female and 6 were male. Five patients were phakic and 4 pseudophakic. Average donor age was 67±9 years., Results: During routine postoperative consultation, specular microscopy images showed suspected recurrence of guttae in 10 eyes after DMEK. Presence of guttae was subsequently confirmed in 9 cases by confocal microscopy and in one case by histology. Six out of 10 patients (60%) had undergone bilateral DMEK, but all only showed recurrence of guttae in one eye. In 9 eyes guttae recurred after primary DMEK, while in one eye recurrence was after a re-DMEK that has been performed 56 months after the first DMEK with no signs of guttae after primary DMEK. Suspected guttae were visible on specular microscopy images already at 1 month after DMEK in most cases.No guttae had been noted during donor cornea processing in the eye bank. Preoperative donor endothelial cell density (ECD) had been 2643±145 cells/mm2 and 1-year postoperative ECD was 1047±458 cells/mm2 (n=8)., Conclusion: Recurrence of guttae after DMEK is most likely due to guttae on the donor graft that were not detectable by routine slit-lamp and light-microscopy evaluation in the eye bank. Better screening methods for guttae detection need to be developed for eye banks to avoid releasing tissue for transplantation that contains guttae or is prone for postoperative guttae formation., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To evaluate the effect of graft preparation and organ-culture storage on endothelial cell density (ECD) and viability of Descemet membrane endothelial keratoplasty (DMEK) grafts., Methods: DMEK grafts (n=27) were prepared at Amnitrans EyeBank Rotterdam from 27 corneas (15 donors) that were eligible for transplantation but could not be allocated due to the COVID-19-related cancellation of elective surgeries. Cell viability (by Calcein-AM staining) and ECD of 5 grafts originally scheduled for transplantation, were evaluated on the originally planned surgery day, whereas 22 grafts from paired donor corneas were evaluated either directly post-preparation or after 3-7 days of storage. ECD was analyzed by light microscopy (LM ECD) and Calcein-AM staining (Calcein-ECD) RESULTS: Light microscopy (LM) evaluation of all grafts showed an unremarkable endothelial cell monolayer directly after preparation. However, median Calcein-ECD for the 5 grafts initially allocated for transplantation was 18% (range 9-73%) lower than median LM ECD. For the paired DMEK grafts, Calcein-ECD determined by Calcein-AM staining on the day of graft preparation and after 3-7 days of graft storage showed a median decrease of 1% and 2%, respectively. Median percentage of central graft area populated by viable cells after preparation and after 3-7 days of graft storage was 88% and 92%, respectively., Conclusions: Cell viability of most of the grafts will not be affected by preparation and storage. Endothelial cell damage may be observed for some grafts within hours after preparation with insignificant additional ECD changes during 3-7 days of graft storage. Implementing an additional post-preparation step in the eye bank to evaluate cell density before graft release for transplantation may help to reduce postoperative DMEK complications., (© Author(s) (or their employer(s)) 2022. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

Endothelial keratoplasty has replaced traditional penetrating keratoplasty for the treatment of corneal endothelial dysfunction. It offers faster, more predictable, stable visual recovery and low rejection rates while the surgery itself is less invasive. Descemet membrane endothelial keratoplasty (DMEK) is currently the gold standard for the treatment of Fuchs endothelial dystrophy, bullous keratopathy, and corneal edema after cataract surgery. Its favorable long-term outcomes are increasingly reported by large study groups. This review summarizes the current literature on new DMEK techniques, including size and shape modifications, new graft delivery techniques, and surgical pearls for challenging cases like eyes with glaucoma, glaucoma tubes, and failed penetrating keratoplasties.

Abstract: Herein, we report the outcomes of intrastromal Descemet membrane (DM) transplantation in corneas with advanced keratoconus. Three eyes (three patients) showed advanced keratoconus. No eye underwent prior UV-cross-linking or any other ocular surgery. In all eyes, A donor DM was implanted into a mid-stromal pocket and clinical outcomes were evaluated up to 24 months after surgery. All procedures were uneventful. Up to 24 months postoperatively, the DM graft was well-positioned and barely visible within the recipient stroma; all corneas were clear. No eye showed signs of keratoconus progression throughout the follow-up. No changes were observed in uncorrected and best contact lens corrected visual acuity, central endothelial cell density, corneal thinnest point pachymetry, and maximum keratometry values. No early or late postoperative complications were observed. Intrastromal DM transplantation may be an alternative to intrastromal Bowman layer transplantation in advanced keratoconus, to postpone deep anterior lamellar or penetrating keratoplasty., Competing Interests: G. Melles is a consultant for DORC International/Dutch Ophthalmic USA and SurgiCube International. The remaining authors have no funding or conflicts of interest to disclose., (Copyright © 2020 Contact Lens Association of Ophthalmologists.)

For nearly a century, the definitive treatment of many corneal dystrophies and ectactic disorders was limited to penetrating keratoplasty, but over the past 2 decades, a surge of surgical innovation has propelled the treatment of many corneal diseases to more targeted approaches with significantly better visual outcomes. Anterior stromal diseases were first changed through endothelial-sparing techniques, such as deep anterior lamellar keratoplasty, but have more recently transitioned to stromal-sparing approaches. Ultraviolet corneal crosslinking strengthens the cornea and halts progression of keratoconus in >90% of cases. Intracorneal ring segment and corneal allogenic ring segment implantation offer methods to flatten ectatic corneas. However, Bowman layer transplantation - inlay and more recently onlay techniques - has shown promise for treating advanced keratoconus and preventing keratoplasty. The advent of endothelial keratoplasty radically changed the treatment of corneal endothelial dysfunction, and Descemet membrane endothelial keratoplasty specifically offers an average postoperative visual acuity of 20/25 (0.8) with only 8.8% of grafts requiring retransplantation in the first 5 years. Here, we review the rapid innovations for surgical treatment of corneal diseases, spanning from endothelial keratoplasty and endothelial regeneration to anterior lamellar keratoplasty and stromal augmentation, highlighting key steps which may be moving us closer to a "postkeratoplasty" world., (© 2021 The Author(s) Published by S. Karger AG, Basel.)

Purpose: To identify and determine differences in lipid profile of aqueous humour (AH) in patients with Fuchs endothelial corneal dystrophy (FECD)., Methods: Lipidomic profile of eight AH samples of FECD patients and 10 control samples was analysed. Patients with previous history of anterior segment surgery, anterior segment pathology or intraocular injections were excluded. Topical ocular medications within the last 6 months were reported. Aqueous humour (AH) was obtained during the first step of Descemet membrane endothelial keratoplasty in FECD patients and during refractive lensectomy in the control group. Lipidomic ultra-performance liquid chromatography mass spectrometry was used to perform an optimal profiling of glycerolipids, sterol lipids, sphingolipids and glycerophospholipids. Metabolite extraction was accomplished by fractionating the samples into pools of species with similar physicochemical properties., Results: The levels of 27 of 110 lipids change significantly in the AH of FECD eyes when compared to control samples. The concentration of most diacylglycerophosphocholines and 1-ether, 2-acylglycerophosphocholines increases in the AH of FECD eyes when compared to healthy controls. In addition, eight sphingomyelins and up to two long-chain highly unsaturated cholesteryl esters present higher levels in FECD samples when compared to controls., Conclusion: The lipid composition of AH in FECD patients differs from that of healthy subjects. Those changes may reflect oxidative stress-related changes in the lipid metabolism of the corneal endothelial cells in FECD., (© 2017 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Objectives: To evaluate the clinical outcome of the first 450 consecutive cases after Descemet membrane endothelial keratoplasty (DMEK), as well as the effect of standardization of the technique., Material and Methods: Comparison between 3 groups: Group I: (cases 1-125), as the extended learning curve; Group II: (cases 126-250), transition to technique standardization; Group III: (cases 251-450), surgery with standardized technique. Best corrected visual acuity, endothelial cell density, pachymetry and intra- and postoperative complications were evaluated before, and 1, 3 and 6 months after DMEK., Results: At 6 months after surgery, 79% of eyes reached a best corrected visual acuity of≥0.8 and 43%≥1.0. Mean preoperative endothelial cell density was 2,530±220 cells/mm2 and 1,613±495 at 6 months after surgery. Mean pachymetry measured 668±92 μm and 526±46 μm pre- and (6 months) postoperatively, respectively. There were no significant differences in best corrected visual acuity, endothelial cell density and pachymetry between the 3 groups (P > .05). Graft detachment presented in 17.3% of the eyes. The detachment rate declined from 24% to 12%, and the rate of secondary surgeries from 9.6% to 3.5%, from group I to III respectively., Conclusions: Visual outcomes and endothelial cell density after DMEK are independent of the technique standardization. However, technique standardization may have contributed to a lower graft detachment rate and a relatively low number of secondary interventions required. As such, DMEK may become the first choice of treatment in corneal endothelial disease., (Copyright © 2014 Sociedad Española de Oftalmología. Published by Elsevier España, S.L.U. All rights reserved.)

Background: The procedure of posterior lamellar keratoplasty has now become established as first choice therapy for the treatment of corneal endothelial diseases, with Descemet membrane endothelial keratoplasty (DMEK) as the most recent refinement of endothelial keratoplasty techniques. In this study the outcome of 400 consecutive cases after standardized no-touch DMEK was evaluated., Methods: This was a non-randomized retrospective clinical study of 400 consecutive eyes in 321 patients who underwent standard DMEK. Outcome measures included best corrected visual acuity (BCVA) preoperatively and postoperatively at 1, 3 and 6 months, endothelial cell density (ECD), pachymetry and complications within the first 6 months. In addition two subgroups were analyzed (subgroup I cases 1-200 and subgroup II cases 201-400)., Results: At 6 months postoperatively 80 % of all eyes had a BCVA of ≥ 20/25 (≥ 0.8), 44 % of ≥ 20/20 (≥ 1.0) and 14 % of ≥ 20/18 (≥ 1.2). There were no significant differences between the two subgroups. The mean ECD preoperatively was 2,542 (± 217) cells/mm(2) and 6 months postoperatively 1,622 (± 500) cells/mm(2). The mean ECD decrease was 36 % 6 months after DMEK. No difference between the subgroups was noted. In 5 % a re-operation was needed of which 75 % were performed in subgroup I., Conclusion: With the standardized no-touch DMEK technique a rapid and nearly complete visual rehabilitation as well as ECD values similar to earlier endothelial keratoplasty techniques can be achieved. Therefore DMEK may become the preferred treatment for corneal endothelial disorders.

Purpose: The aim of this study was to evaluate the visual outcome and endothelial cell density in the first series of 100 eyes after Descemet membrane endothelial keratoplasty (DMEK) for the treatment of Fuchs endothelial dystrophy., Design: This was a non-randomised prospective clinical trial., Methods: The first 100 consecutive eyes (87 patients) that underwent DMEK (i. e., transplantation of an isolated donor Descemet membrane carrying its endothelium) for Fuchs endothelial dystrophy were evaluated. In all eyes, the best corrected visual acuity (BCVA) as well as the endothelial cell density (ECD) were measured before and at one, three and six months after surgery., Results: In eyes with a functional DMEK graft and good visual potential (n = 78), the BCVA was > or = 20 / 40 (> or = 0.5) in 79 % after 1 month, 94 % after 3 months, and 96 % after six months; > or = 20 / 25 (> or = 0.8) in respectively 54 %, 64 %, and 74 %, and > or = 20 / 20 (> or = 1.0) in respectively 26 %, 36 %, and 45 %. In this group, ECD averaged 2630 (+/- 190) cells/mm (2) before, and 1800 (+/- 540) cells/mm (2) at six months after surgery (n = 76). In 15 eyes, a secondary "Descemet stripping endothelial keratoplasty" (DSEK) was performed. When the outcomes of DMEK and secondary DSEK procedures were combined, 91 % reached a BCVA of > or = 20 / 40 (> or = 0.5), 65 % > or = 20 / 25 (> or = 0.8) and 38 % > or = 20 / 25 (> or = 1.0) at six months after surgery (n = 93). For the whole group, ECD averaged 2620 (+/- 190) cells/mm (2) before, and 1730 (+/- 590) cells/mm (2) at six months after surgery (n = 89)., Conclusion: DMEK may provide relatively quick and nearly complete visual rehabilitation in a majority of patients operated on for Fuchs endothelial dystrophy. Endothelial cell survival may be similar to earlier types of endothelial keratoplasty. Early graft detachment (19 cases) was the main complication in this first series of DMEK surgeries., (Georg Thieme Verlag KG Stuttgart, New York.)

Purpose: To report the two-year results of Descemet membrane endothelial keratoplasty (DMEK) for managing corneal endothelial disorders., Methods: Non-randomized prospective clinical trial. A DMEK was performed in ten patients with Fuchs' endothelial dystrophy or bullous keratopathy. A 3.5 mm clear corneal incision was made and "under air" DM was stripped off from the posterior stroma. A 9.0 mm diameter, organ cultured donor DM roll was inserted into a recipient anterior chamber, positioned into the posterior stroma and secured by completely filling the anterior chamber with air for 30 minutes., Results: Three eyes showed complete detachment of the tissue; this was managed by a secondary Descemet stripping endothelial keratoplasty procedure. The remaining seven eyes had a best corrected visual acuity of >or=0.7 in three eyes (43%) at one month, in five eyes (71%) at six months, and in six eyes (86%) at one and two years. At six months, the endothelial cell density averaged 2039 (+/-373) cells/mm2 (n=7), at one year 1925 (+/-267) cells/mm2 (n=7) and at two years 1730 (+/-400) cells/mm2 (n=6)., Conclusions: DMEK may provide quick and nearly complete visual rehabilitation. Since the donor tissue can be stripped from donor corneo-scleral rims, the procedure may be readily accessible to most corneal surgeons.

Purpose: To investigate whether trypan blue has a toxic effect on cultured retinal pigment epithelial (retinal pigment epithelium) cells., Design: Experimental study with a direct live/dead cell staining technique using fluorescent dyes., Methods: Cultured human retinal pigment epithelium cells were exposed for 5 minutes to various concentrations of trypan blue (0.06%, 0.15%, 0.30%), and cell viability was confocally measured., Results: No increased cell death was found in cultures incubated in any of the trypan blue concentrations used., Conclusion: These findings indicate that a short exposure of trypan blue does not have a toxic effect on cultured retinal pigment epithelium cells.

Objectives: To describe the refractive results of cataract surgery after photorefractive keratectomy (PRK) for patients with myopia, and to find a more accurate method to predict intraocular lens (IOL) power in these cases., Design: Nonrandomized, retrospective clinical study., Patients and Methods: Nine patients (15 eyes) who underwent cataract surgery after prior PRK to correct myopia were identified. The medical records of both the laser and cataract surgery centers were reviewed., Main Outcome Measures: Eight different keratometric values (K values; measured or calculated) were entered into 3 different IOL calculation formulas: SRK/T, Holladay 1, and Hoffer Q. The actual biometry and IOL parameters were used to predict postoperative refraction, which was compared with the actual refractive outcome. Also, the relative underestimation of the refractive change in corneal dioptric power by keratometry after PRK was calculated., Results: In 7 of 15 eyes, IOL exchange or piggybacking was performed because of hyperopia. Retrospectively, the most accurate K value for IOL calculation was found to be the pre-PRK K value corrected by the spectacle plane change in refraction. Use of the Hoffer Q formula would have avoided postoperative hyperopia in more cases than the other formulas. The mean underestimation of the change in corneal power after PRK varied from 42% to 74%, depending on the method of calculation., Conclusion: The predictability of IOL calculation for cataract surgery after PRK can be improved by using a corrected, refraction-derived K value instead of the measured, preoperative K value.

Purpose: To describe a new surgical technique for deep, anterior lamellar keratoplasty using a viscoelastic for dissection of Descemet's membrane (DM) from the posterior stroma., Methods: Through a paracentesis, aqueous was exchanged by air to visualize the posterior corneal surface-i.e., the air-to-endothelium interface. Using the interface as a reference plane, a 30 gauge needle was inserted into the cornea to just anterior to DM. Viscoelastic was injected to separate DM from the posterior stroma, and a recipient, anterior lamella was excised. A full-thickness donor button was sutured into the recipient bed, after stripping its DM., Results: In 25 eye bank eyes, the procedure could be completed in 20 eyes; in 5 eyes, DM ruptured during visco-dissection. With light microscopy, dissection depth was located at the level of DM. In two patient eyes the procedure could be completed. In a third patient eye DM ruptured during visco-dissection, and the procedure was converted into a penetrating keratoplasty., Conclusion: Using visco-dissection, a lamellar keratoplasty can be performed quickly, with the donor-to-recipient interface just above the recipient DM, i.e., with a nearly perfect anatomical replacement of all corneal stroma. There is substantial risk of rupture or microperforation of DM during surgery.

Background: A capsulorhexis may be difficult to perform in the absence of a red fundus reflex., Patients and Methods: After application of 0.3 mL trypan blue 0.1%, a quick and homogeneous staining of the anterior lens capsule was obtained in 100 patients with a mature cataract, to visualize the capsulorhexis during a phacoemulsification procedure., Results: No adverse reactions related to the dye were observed up to 18 months after surgery., Conclusion: Trypan blue staining of the anterior lens capsule may therefore be a safe technique to facilitate the performance of a capsulorhexis in the absence of a red fundus reflex.

Purpose: To describe a new surgical technique for posterior corneal transplantation., Methods: An elderly patient had painful, pseudophakic bullous keratopathy with low visual potential. Through a 9.0-mm scleral tunnel incision, a midstromal pocket was dissected across the cornea, and a posterior lamellar disk 7.0-mm in diameter, which consisted of posterior stroma, Descemet membrane, and endothelium, was excised. A similarly shaped donor posterior disk was implanted in the recipient opening without suture fixation, and the scleral incision was sutured., Results: Throughout the postoperative period, the posterior corneal transplant remained clear and in position. Three months after surgery, the "suture-in" astigmatic error was 3.5 diopters. Pachymetry measured 0.44 mm., Conclusion: Posterior lamellar keratoplasty may be a new surgical approach with which to manage corneal endothelial disorders.

A capsulorhexis may be difficult to perform in the absence of a red fundus reflex. Using 0.1 mL of trypan blue 0.1% to stain the anterior capsule in 30 patients with a mature cataract enabled us to visualize the capsulorhexis during phacoemulsification. No adverse reactions were observed up to 12 months after surgery. Trypan blue staining of the anterior capsule appears to be a safe technique to facilitate the performance of a capsulorhexis in the absence of a red fundus reflex.

Purpose: To describe a surgical technique to visualize the depth of corneal incisions and lamellar stromal dissections during surgery., Methods: In porcine cadaver eyes, the aqueous was exchanged by air. Thus an air-to-endothelium interface (i.e., a useful optical surface) was created at the posterior corneal surface. The air-to-endothelium interface was used as a reference plane to visualize the corneal thickness and the relative depth of corneal incisions and dissections. Freehand peripheral corneal incisions, tangential keratotomy incisions, and lamellar stromal dissections were made at an intended corneal depth of 60, 80, and 99%. Light microscopy was used to measure the relative depth of the incisions and dissections., Results: Achieved depth for peripheral corneal incisions averaged 65.2+/-5.3%, 78.8+/-5.1%, and 93.4+/-6.0%, respectively (p<0.05); and for tangential keratotomy incisions, 68.2+/-7.3%, 83.2+/-4.4%, and 95.8+/-3.6%, respectively (p<0.05). Achieved depth for lamellar stromal dissections averaged 58.3+/-9.4%, 81.1+/-3.4%, and 94.4+/-1.5%, respectively (p<0.05). Microperforations occurred with three incisions made at 99% intended depth., Conclusion: During surgery, the depth of incisions and lamellar dissections relative to the corneal thickness can be visualized by filling the anterior chamber with air (i.e., by creating an optical interface at the posterior corneal surface).

Purpose: To design a surgical technique for transplantation of posterior corneal tissue, while leaving the recipient anterior cornea intact., Methods: In human cadaver eyes, and in a cat and monkey model, recipient eyes had an 8.0-mm limbal incision made with a diamond blade set to 50% of central pachymetry. A stromal pocket was created across the cornea, and a 6.0-mm diameter posterior lamellar disc was excised. A donor posterior disc was implanted into the recipient opening, and the limbal incision was sutured. The procedure was evaluated with keratometry, biomicroscopy, endothelial (supra)vital staining, and light microscopy., Results: In human cadaver eyes, post-operative astigmatism averaged 1.2 D (SD, +/- 0.6 D). Posterior transplants showed an intact endothelial cell layer with 1.0% (SD, +/- 1.2%) of cell death. In the animals, six (75%) eyes had clear transplants 2 weeks after surgery; one of these eyes later developed an allograft rejection. Two (25%) eyes showed corneal decompensation, because of inverted implantation of the donor disc. Microscopy showed minimal scarring at the donor-to-host interface and a normal wound-healing response at the posterior stromal wound edges., Conclusion: In experimental models, posterior lamellar keratoplasty can be performed through a limbal incision and a mid-stromal pocket. The procedure may be a potential alternative in the surgical management of corneal endothelial disorders.

Purpose: To evaluate the predictability of the depth of stromal pockets made in the posterior cornea for the excision of anterior or posterior lamellar corneal buttons with a planned thickness., Methods: Stromal corneal pocket dissections were created in human eye bank eyes by making a peripheral arcuate keratotomy incision at 60, 80, or 95% of central pachymetry and creating a pocket from the bottom of the incision across the cornea. Pocket depth was measured by pachymetry immediately after surgery and by light microscopy., Results: Mean achieved central pocket depth differed by 0.03+/-0.03 mm from the intended depth. Variation in depth across the pocket decreased from 0.07+/-0.02 mm for pockets made at 60% of the intended depth to 0.05+/-0.01 mm for pockets made at 80% depth, and 0.04+/-0.02 mm for pockets made at 95% depth (p < 0.01). Pachymetric and histological measurements of relative pocket depth averaged 64+/-9% and 73+/-7%, respectively, for pockets made at 60% of the intended depth, 82+/-7% and 86+/-3% for pockets made at 80% depth, and 91+/-7% and 92+/-3% for pockets made at 95% depth. The difference between pachymetric and histological relative pocket depth measurements decreased with deeper pocket depth (p < 0.01)., Conclusions: In the posterior cornea, stromal pockets can be created to within 30 microm from the intended depth. Variation in depth throughout the pocket decreases with deeper pocket depth. Pachymetry is a reliable method to check the achieved pocket depth during surgery; the accuracy of pachymetry readings improves with deeper pocket depth.

We designed a study to evaluate healing in reopened-and-sutured (RAS) keratotomy wounds to determine the efficacy of reoperations in treating radial keratotomy overcorrections. Using light and transmission electron microscopy, we compared stromal scar tissue organization (transverse fibroblast orientation and collagen fiber continuity across the wound) in RAS wounds and in sutured and unsutured control wounds in 18 monkey eyes one to nine weeks after surgery. Wound healing morphology of RAS wounds varied with the interval between reoperation and termination of the experiment. Scar tissue organization was sagittal at one week postoperatively, transverse in the anterior and mid regions after four weeks, and transverse over the entire wound after nine weeks. Sutured wounds showed a similar pattern of healing, although transverse scar tissue organization was restricted to the anterior and mid regions in the late healing phases. In contrast, unsutured wounds showed a temporary, transverse scar tissue organization over the entire wound depth at two to four weeks and a progressive reorientation of the mid and posterior scar tissue sagittal to the wound at later intervals. The results suggest that reopening and suturing keratotomy incisions to treat radial keratotomy overcorrections may be effective through a myopic shift induced by sutured wound apposition and long-term wound remodeling, contraction, or both.

In the unsutured partial thickness penetrating wounds of the cornea, the epithelium migrates over the wounded stromal surface prior to the onset of stromal regeneration. To determine the possible affects of the epithelial ingrowth on the organization of the stromal scar tissues, the healing of unsutured and sutured wounds was compared immunohistochemically. Immunostaining patterns for fibronectin, types III, VI and VII collagen, keratan sulfate proteoglycan (KSPG), and intermediate filament-associated protein (IFAP 130) in fibroblasts, were analyzed in unsutured and adjacent sutured keratotomy wounds in monkeys, at 2-9 weeks after surgery. At 2-4 weeks, fibronectin, type III and type VI collagen showed a lamellar interweaving pattern across unsutured wounds that was absent in sutured wounds. Type VII collagen was detected along the entire depth of regenerated stroma in unsutured wounds, but not in sutured wounds indicating that the epithelium had formerly been present in the regenerated stroma in unsutured wounds. Fibroblasts in both types of wounds expressed IFAP 130, but staining was more pronounced in sutured wounds. At 5-9 weeks, cellular re-activation, as judged from the expression for IFAP 130, was concomitant with a loss of lamellar interweaving with fibronectin, type III and type VI collagen across unsutured wounds, and proceeded in a posterior to anterior direction. In contrast, in sutured wounds, lamellar interweaving was established in anterior to posterior direction. At all postoperative times, unsutured and sutured wounds showed minimal staining for KSPG in the anterior scar.(ABSTRACT TRUNCATED AT 250 WORDS)

Objective: To evaluate epithelial-stromal interactions in the healing of stromal wounds and the relationship of such interactions to regional variations in healing throughout keratotomy wounds., Methods: Ten radial keratotomy autopsy specimens were studied by using light and transmission electron microscopy., Results: Underneath epithelial plugs, the epithelial-stromal interface was characterized by three adjacent morphological zones: a duplicated basement membrane complex, a zone that resembled Bowman's layer, and a third zone with collagenous fiber orientation parallel to the plugs. Scar tissue orientation was transverse at the base of the plug, and sagittal in deeper wound regions., Conclusions: Basement membrane duplication and a Bowman's layer-like region underneath a plug may result from complicated epithelial-stromal interaction. Asymmetrical organization of the scar, with subepithelial transverse and sagittal deeper scar tissue orientation, may characterize radial keratotomy wound healing, and may relate to variations in final refractive effect.

Objective: To determine regional differences in stromal wound healing morphologic features in long-term radial keratotomy wounds., Methods: Unsutured, semiradial, nonperforating wounds in seven monkeys and 10 human autopsy specimens obtained 3.5 to 52 months after surgery were analyzed using light, transmission, and fluorescent microscopy., Results: Monkeys showed fast healing, whereas all human specimens had one or more incisions containing a superficial epithelial plug. Completely healed wounds in both models had fibroblast orientation and ultrastructural "pseudolamellar" (ie, colinear collagen fiber) continuity across the anterior wound, compared with disorganization of the midposterior scar., Conclusions: Regional differences in healing rates, mechanical factors associated with epithelial plug elimination, intrinsic tissue characteristics, and/or induction of pseudolamellar repair by the epithelial plug may explain variation in healing within an unsutured corneal wound.

For the same diamond blade extension, uphill (centripetal) radial keratotomy incision direction achieves greater depth and consequently greater refractive effect than downhill (centrifugal) incisions. To determine which factors may account for this difference, two uphill and two downhill incisions were made with a double-edged diamond blade set to 90% central pachometry in 26 human donor eyes at 15 or 60 mm Hg. Uphill incisions made with the perpendicular blade had greater mean incision depth than downhill incisions made with the oblique blade at 15 mm Hg (83.6 +/- 3.9% and 68.2 +/- 5.2%) (p < 0.0005) and at 60 mm Hg (86.3 +/- 3.1% and 79.7 +/- 1.7%) (p < 0.0005). Uphill and downhill incisions both made with the perpendicular blade had equal depth (85.4 +/- 4.9% and 83.7 +/- 3.5%) (p > 0.1). The perpendicular blade edge created a straight, and the oblique edge an S- or J-shaped, histological incision configuration. Corneal profile pictures taken during each incision showed the knife to tilt opposite of the incision direction and to move at a constant angle to the limbal plane, producing a smaller optical clear zone (OCZ) in the posterior stroma than intended with uphill incisions. Greater refractive effect with uphill incisions may be explained by the perpendicular blade being more effective in incising corneal lamellae, and the creation of a smaller posterior OCZ. Intraocular pressure variations during surgery may affect achieved incision depth of downhill, but not of uphill, incisions.

Background: Clinical observation suggests the location, orientation, direction, and postoperative time of unsutured corneal wounds may affect healing., Methods: We studied wound depth, deviation, width, and healing phases in central to peripheral portions of superior and inferior transverse incisions, and centripetal and centrifugal semiradial incisions. Healing phases were quantified by the amount of epithelial plug elimination and by fibroblast orientation to the wound., Results: Healing rates varied among individual monkeys. Complete stromal wound closure was seen as early as 2.5 months postoperative, whereas epithelial plugs were present up to 11 months. Average depth did not differ between superior (61.7% +/- 13.4%) and inferior transverse incisions (66.3% +/- 8.2%) (p > .1); all incisions deviated toward the limbus (28.9 degrees +/- 19.9 degrees and 31.0 degrees +/- 19.8 degrees) (p > .1). Superior transverse wounds showed advanced healing compared to mate inferior wounds (p < .05). Compared to centrifugal wounds, centripetal wounds had greater depth (48.1% +/- 7.3% versus 76.0% +/- 7.0%) (p < .0005), greater width (17.2 microns +/- 4.5 microns versus 27.8 microns +/- 6.9 microns) (p < .01), and earlier healing phases (p < .025). With longer postoperative time intervals, fibroblast orientation appeared to change from a relatively perpendicular to a parallel orientation to the wound., Conclusions: Transverse incisions may be difficult to perform perpendicular to the corneal surface. Superior transverse wounds may heal faster than mate inferior wounds, and centrifugal radial wounds may heal faster than centripetal wounds. Differences in semiradial wound morphology may be related primarily to incision depth and postoperative time; incision direction may also affect wound healing.

Radial keratotomy (RK) is currently performed with four or eight semi-radial incisions. To evaluate the effect of a theoretically more stable three-incision RK pattern, centripetal incisions were made in 16 human donor eyes (eight pairs), using a double-edged diamond blade set to 90% of central pachymetry and a 3.5 mm optical clear zone. Intraocular pressure was maintained at 15 mm Hg during surgery and while keratometry readings were made. One randomly selected eye of each pair had three radial incisions made at 12, 4 and 8 o'clock; the other eye had four radial incisions at 12, 3, 6, and 9 o'clock. Corneal flattening was 6.08 diopters (D) with four incisions and 4.84 D with three incisions (P less than .05). Astigmatism increased 0.44 D and 0.69 D, respectively (P greater than .1). Histologically measured mean incision depth (77.4%) did not differ significantly between the groups (P greater than .1). This study shows that 80% of the effect of a four-incision RK pattern can be obtained with a theoretically more stable three-incision pattern.

The majority of ophthalmic surgeons who perform radial keratotomy make incisions from the optical clear zone to the limbus (downhill; centrifugal), instead of from the limbus to the optical clear zone (uphill; centripetal). To compare the efficacy of these techniques, one surgeon performed keratotomy incisions in 10 eyes of 5 monkeys using the same double-edged diamond blade set to 80% of central pachometry. Four or eight centrifugal (downhill) and centripetal (uphill) incisions were made in each eye. Achieved incision depth was measured by light microscopy 2.5 to 8 months postoperative. Downhill incision depth averaged 46% (range 38% to 61%), whereas uphill incision depth averaged 74% (range 53% to 87%) (P less than .0005). In both groups, incision deviation from the perpendicular (lateral tilt error) was greatest adjacent to the optical clear zone (P less than .01). These differences may be explained by tilt error (forward or backward) or by the perpendicular front cutting action of a vertical blade being more effective than the angled blade.

We compared corneal wound healing in 25 clear transplants with 26 keratotomy specimens and sutured and unsutured corneal wounds in a monkey model. Monkey wounds healed faster than human wounds, but healing time within the same species varied. Sutured wounds were characterized by subepithelial fibroplasia, recovery of collagen fiber continuity and absence of epithelial plugs. Unsutured wounds had no subepithelial fibroplasia but had fibroblasts and collagen fiber orientation parallel to wounds. Unsutured wounds in corneas containing sutures had subepithelial fibroplasia, and fibroblast orientation and fiber deposition parallel to the wound. Epithelial ingrowth and incarceration of Bowman's layer and/or Descemet's membrane in unsutured wounds appeared to disrupt wound healing. Abnormalities in wound healing in sutured or unsutured wounds are associated with lamellar distortion, a modified inflammatory response, and individual wound healing responses.