Bevacizumab in High-Risk Corneal Transplantation: A Pilot Multicenter Prospective Randomized Control Trial

PURPOSE

To determine the efficacy of local (subconjunctival and topical) bevacizumab (Avastin) treatment in patients undergoing vascularized high-risk corneal transplantation.

DESIGN

Pilot, prospective, randomized, double-blind, placebo-controlled clinical trial conducted at 5 clinical centers in the United States, India, and Brazil.

PARTICIPANTS

Patients aged > 18 years undergoing high-risk penetrating keratoplasty, defined as corneal neovascularization (NV) in 1 or more quadrants ≥2 mm from the limbus or extension of corneal NV to the graft-host junction in a previously failed graft.

METHODS

Patients were randomized to receive subconjunctival bevacizumab (2.5 mg/0.1 ml) or placebo at the time of surgery, followed by topical bevacizumab (10 mg/ml) or topical placebo, administered 4 times per day for 4 weeks.

MAIN OUTCOME MEASURE

The 52-week endothelial immune rejection rate.

RESULTS

Ninety-two patients were randomized to receive bevacizumab (n = 48) or control (n = 44). The 52-week endothelial rejection rate was 10% in the bevacizumab group and 19% in the control group (P = 0.20). Post hoc, extended follow-up at the lead study site showed an endothelial rejection rate of 3% in the bevacizumab group and 38% in the control group (P = 0.003). Treatment with bevacizumab was found to have a hazard ratio of 0.15 (95% confidence interval, 0.03-0.65, P = 0.01) in a post hoc Cox regression analysis.

CONCLUSIONS

In patients undergoing vascularized high-risk corneal transplantation, there was no statistically significant difference in the rate of endothelial rejection at 1 year in the bevacizumab treatment group compared with the control group. This study may have been underpowered to detect a difference between treatment groups, and taken together, our data suggest that, in the current trial design, bevacizumab has a positive but not (yet) significant effect on endothelial rejection.

[Clinical analysis of penetrating keratoplasty for infants with congenital corneal opacity]

Objective: To investigate the corneal graft survival and related risk factors of primary penetrating keratoplasty in congenital corneal opacity infants. Methods: It was a retrospective cohort study. Data were collected from forty-two infants (51 eyes) who were aged ≤12 months and diagnosed with congenital corneal opacity in Beijing Tongren Hospital and Beijing Anzhen Hospital from January 1, 2017 to January 31, 2018. The mean age at surgery was (5.7±2.2) months (3-12 months). The mean follow-up duration was (28.6±2.6) months (24-33 months). All the patients underwent penetrating keratoplasty. The status of the corneal grafts and complications were observed and recorded during the regular follow-up. The survival probabilities were estimated by using the Kaplan-Meier and Log-rank test. The graft survival between different influence factors was analyzed by using the χ² test. Results: The Kaplan-Meier survival rates for penetrating keratoplasty were 84.3% (43/51) at 6 months, 78.4% (40/51) at 12 months and 60.8% (31/51) at the last follow-up. The presence of corneal neovascularization was significantly correlated with graft failure (χ²=5.264, P=0.022). The graft survival differed between eyes receiving combined surgery and mere penetrating keratoplasty and in eyes with varied surgical indications (P=0.039, <0.01). Increased intraocular pressure (7 eyes, 13.7%) and persistent epithelial defects (7 eyes, 13.7%) were the most common postoperative complications, followed by complicated cataract (4 eyes, 7.8%) and posterior capsule opacification (2 eyes, 3.9%). Conclusions: The graft survival rate was satisfactory following pediatric keratoplasty although it had a tendency to decrease with the follow-up time. Corneal neovascularization was a major risk factor of graft failure. Surgical indications and procedures also had a certain effect on the graft survival.

Outcomes of Descemet's stripping endothelial keratoplasty in eyes with failed therapeutic penetrating keratoplasty

PURPOSE

To report the results of Descemet's stripping endothelial keratoplasty (DSEK) for failed therapeutic penetrating keratoplasty (PK).

METHODS

Twenty-seven eyes of 27 patients undergoing DSEK for failed therapeutic PK were analysed.

RESULTS

The mean age of the patients was 36 ± 13.9 years (range: 14-70 years). The median size of the therapeutic graft was 10 mm (inter-quartile range; IQR 9.5-11 mm). Descemet's membrane stripping was performed in all eyes. Graft clarity was achieved in 20/27 eyes. Six eyes had primary graft failure, and one had interface keratitis in the early postoperative period. In all eyes with primary graft failure, there was progressive stromal vascularization, which led to haziness in the graft. Late postoperative complications were rejection in four eyes, infection in two eyes, secondary graft failure in one eye and vortex keratopathy in one eye. Graft size was found to be a significant risk factor for graft rejection in this series. At the last follow-up visit, the best-corrected visual acuity was ≥20/40 in 5/27 eyes (18.5%), 20/60-20/40 in 12/27 eyes (44.4%), 20/100-20/60 in 3/27 eyes (1.5%) and ≤20/200 in 7/27 eyes (25.9%).

CONCLUSIONS

Considering the limited success of repeat PK in failed large therapeutic keratoplasty, DSEK is a viable option for visual rehabilitation in these eyes, however; visual acuity may be limited due to sub-epithelial/stromal or interface scarring.

Survival of mushroom keratoplasty performed in corneas with postinfectious vascularized scars

PURPOSE

To report the visual outcomes and graft survival rates of mushroom keratoplasty for the treatment of postinfectious corneal scars.

DESIGN

Prospective, noncomparative, interventional case series.

METHODS

A microkeratome-assisted mushroom-shaped keratoplasty was performed in 31 eyes of 31 patients with a central vascularized full-thickness leukoma, resulting from infectious keratitis of various origin (herpes simplex virus, n = 16; bacteria, n = 10; Acanthamoeba, n = 5), with healthy endothelium. The donor graft consisted of a large anterior stromal lamella (9.0 mm in diameter and ± 250 μm in thickness) and a small posterior button (5 to 6 mm in diameter). Visual acuity, refraction, and endothelial cell density were evaluated before surgery, as well as at 12, 24, and 36 months after surgery, and the postoperative graft survival rate was evaluated.

RESULTS

Three years after surgery, in 26 (83.8%) of 31 patients, best spectacle-corrected visual acuity was 20/40 or better with a refractive astigmatism of 4.5 diopters or less. The endothelial cell count at the last follow-up examination averaged 1584 ± 381 cells/mm(2), with an average cell loss of 40.7% from the preoperative value. The survival rate at 3 years was 90.3%, improving to 96.7% when excluding nonimmunologic causes for graft failure.

CONCLUSIONS

Similarly to penetrating keratoplasty, microkeratome-assisted mushroom keratoplasty restores vision in eyes with postinfectious, full-thickness, central corneal scars. For these vascularized corneas at high risk for immunologic rejection, mushroom keratoplasty combines the visual and refractive advantages of large penetrating keratoplasty grafts with the high survival rate of small penetrating keratoplasty grafts.

Necrotizing scleritis following laser therapy for corneal vascularization

A 68-year-old lady presented with irritation in left eye of one-week duration. Examination of her left eye revealed loose corneoscleral sutures with corneal vascularization and white deposit in the cornea in front of the blood vessels. She underwent laser photocoagulation but later developed necrotizing scleritis. We report a rare complication of necrotizing scleritis following laser photocoagulation of the corneal new vessels.

Photodynamic therapy with verteporfin for corneal neovascularization

PURPOSE

To investigate the efficacy of photodynamic therapy with verteporfin for the treatment of patients with corneal neovascularization.

DESIGN

Prospective interventional case series.

METHODS

Eighteen eyes of 18 patients with stable corneal neovascularization who were refractory to conventional treatment were treated with photodynamic therapy with verteporfin (6 mg/m(2)). Five patients were treated following penetrating keratoplasty (PK), and two patients were treated before PK. Anterior segment photography was performed before and after treatment. Best-corrected visual acuity (BCVA) and area of corneal neovascularization were measured.

RESULTS

At the one-year follow-up, 14 eyes (77.8%) showed a decrease in corneal neovascularization, and nine eyes (50.0%) showed complete vascular occlusion. In five patients who had corneal allograft, complete or partial occlusion was achieved in all eyes. Two patients who underwent subsequent keratoplasty did not manifest allograft rejection or revascularization. Seventeen eyes (94.4%) had stable or improved vision. The mean area of corneal neovascularization significantly decreased from 25.5 +/- 14.2 mm(2) to 14.9 +/- 14.6 mm(2) (P < .01), respectively. No significant complications associated with photodynamic therapy were observed except mild stromal haze in one eye.

CONCLUSION

Photodynamic therapy with verteporfin may be effective for the treatment of corneal neovascularization.

[Diseases of the adnexa in the tropics: amnion membrane transplantation for noninfectious trachoma-associated corneal ulcers]

BACKGROUND

Corneal ulcers with fornix shortening associated with late stages of cicatrizing trachoma contribute significantly to blindness in many developing countries. We report on the outcome of ocular surface and fornix reconstruction using amnion membrane transplantation.

PATIENTS AND METHODS

From 2001 to 2005, cryopreserved human amnion membrane without mitomycin C was grafted to 25 eyes of 17 patients with trophic corneal ulcers and symblepharon (cicatrizing trachoma: 19 eyes of 14 patients, Stevens-Johnson syndrome: 4 eyes of 2 patients, alkali burns: 2 eyes of 1 patient) in a controlled case series. Follow-up was done up to 6 months.

STATISTICS

Fischer's exact probability test.

RESULTS

Of 25 eyes, 9 of 19 eyes with trachoma, 3 of 4 eyes with Stevens-Johnson syndrome, and 2 of 2 eyes with chemical burns showed complete reepithelialization and stromal recovery after 28-35 days (mean: 31+/-2.3 days). The primary success rate of trachoma eyes was not significantly different from the other indications (p=0.256). At 6 months post-op, 15 of 19 trachoma eyes (79%) compared to 2 of 6 non-trachoma eyes (33.3%) had developed a recurrence of symblephara (p=0.0592), and 13 of 15 eyes (86.6%) with a cicatricial trachoma compared to 1 of 6 with non-trachoma diagnosis experienced a recurrence of corneal vascularization (difference nonsignificant: p=0.1752). Persistent long-term reepithelialization was observed only in 1 of 19 trachoma eyes (5.3%) versus 4 of 6 non-trachoma eyes (66.7%, p=0.005); 3 of 19 trachoma eyes with a recurrence of ulcers had perforated after 6 months.

CONCLUSIONS

Human amnion membrane without mitomycin C can be used for ocular surface reconstruction in selected patients with cicatrizing trachoma. Its efficacy in the long-term rehabilitation of cicatrizing trachoma seems to be limited due to the progressive scarring.

Long-standing bullous keratopathy is associated with peripheral conjunctivalization and limbal deficiency

OBJECTIVE

To investigate whether peripheral corneal neovascularization in bullous keratopathy (BK) is due to conjunctivalization, a sign of limbal stem cell deficiency.

DESIGN

Observational case-control study.

PARTICIPANTS

Sixteen BK patients.

METHODS

Patients were divided into 2 groups: BK without peripheral neovascularization [NV(-) group; 5 patients, 5 eyes] and BK with neovascularization [NV(+) group; 11 patients, 13 eyes]. Evidence of conjunctivalization was evaluated by periodic acid-Schiff staining of impression cytology samples from the peripheral vascularized cornea. The 2 groups' durations of disease also were compared. Penetrating keratoplasty (PK) was performed in all 16 cases, and the 2 groups' durations of reepithelialization after PK were compared.

MAIN OUTCOME MEASURES

Presence of goblet cells using impression cytology, duration of BK, and duration of postoperative reepithelialization.

RESULTS

Goblet cells were found on the peripheral corneal surface in all eyes in the NV(+) group. However, all eyes in the NV(-) group were negative for goblet cells (P<0.0001). Duration of disease was 14.4+/-5.4 months in the NV(-) group and 66.2+/-65.5 months in the NV(+) group (P = 0.030). Duration of postoperative epithelialization was 6.2+/-2.2 days in the NV(-) group and 28.8+/-36.5 days in the NV(+) group (P = 0.046).

CONCLUSION

Conjunctivalization of the peripheral cornea and delayed postoperative epithelialization in BK patients with NV suggest the presence of limbal stem cell deficiency in such patients. Patients with long-standing disease were found to be more prone to neovascularization. For this reason, early surgery may lead to a better surgical outcome.

Early ocular chemokine gene expression and leukocyte infiltration after high-risk corneal transplantation

PURPOSE

To determine the differential gene expression of chemokine species and leukocyte infiltration of grafts in the early pre-rejection postoperative period after high-risk (HR) compared to normal-risk (NR) corneal transplantation.

METHODS

Fully mismatched and syngeneic corneal grafts were performed in NR (avascular) and HR (vascularized) recipient beds of BALB/c murine hosts. Gene expression levels of a panel of chemokines were determined by a multiprobe ribonuclease protection assay system. The profiles of infiltrating cells into the corneal grafts at the same times were determined immunohistochemically.

RESULTS

Compared to NR transplantation, HR eyes exhibited significantly higher mRNA levels for macrophage inflammatory protein (MIP)-2 and monocyte chemotactic protein-1 (MCP-1) on day 1, and for eotaxin on days 1 and 3 after transplantation. By day 6 after transplantation, still well before graft rejection, significantly higher levels of RANTES, eotaxin, MIP-1alpha, MIP-1beta, MIP-2, and MCP-1 were detected in HR eyes. The overexpression of MIPs in HR eyes correlated with a significant increase in the number of infiltrating macrophages (p<0.01), and neutrophils (p<0.05) in HR compared to NR recipients. Low levels of eosinophil and mast cell infiltration were observed in all grafts, with a modest increase in mast cell infiltration (p<0.05) in HR compared to NR grafts.

CONCLUSIONS

These results suggest that increased expression of gene products for select chemokines, in particular those that mediate recruitment of innate immune cells, in the early period after HR corneal transplantation is related to the enhanced leukocytic infiltration of grafts observed in HR keratoplasty.

Corneal toxicity and inflammation secondary to retained perfluorodecalin

PURPOSE

To describe a case with bullous keratopathy and anterior segment inflammation associated with heavy liquids.

DESIGN

Observational case report.

METHODS

Review of clinical and histopathologic changes.

RESULTS

A 65-year-old patient underwent a pars plana vitrectomy for a rhegmatogenous retinal detachment. Perfluorodecalin was used as a temporary retinal tamponade. After surgery, bubbles of heavy liquid were noted in the anterior chamber. Fifteen months later, severe corneal edema developed, associated with corneal vascularization and keratic precipitates. Removal of heavy liquid through a paracentesis was attempted but the cornea remained edematous, and a penetrating keratoplasty was performed. In the histopathologic examination inflammatory changes from retention of perfluorodecalin were observed. There was a decompensated cornea with florid bullous keratopathy, inflammatory infiltration with vascularization, and deposition of perfluorodecalin within keratocytes and perivascular macrophages.

CONCLUSION

Presence of heavy liquids in the anterior chamber may be associated with an intense inflammatory response and corneal decompensation.

Testing the Angiogenic Potential of Cerebrovascular Malformations by Use of a Rat Cornea Model: Usefulness and Novel Assessment of Changes over Time

OBJECTIVE

This experimental study assessed the usefulness of a rat model of corneal angiogenesis for assessing the angiogenic activity of cerebrovascular malformations (CVMs) over time. It is the first investigation to have focused on dynamic quantification of angiogenesis related to CVMs (i.e., assessing changes over time as opposed to one point in time) and the first to have compared different CVMs and other tissues in this way.

METHODS

The CVM specimens were from 15 randomly selected arteriovenous malformation (AVM) cases, 15 randomly selected cavernous malformation cases, and 2 venous angioma cases. All the samples came from surgical resections performed in the Marmara University Department of Neurosurgery and the Marmara University Institute of Neurological Sciences between January 1998 and January 2003. Glioblastoma multiforme tissues, normal adult brain tissues, and normal brain artery tissues were used as controls. Tissue from each specimen was implanted in one corneal micropocket in each cornea of a single rat, and the level of angiogenic activity in the cornea was graded (low, moderate, or high) at Days 1 through 9 after tissue implantation. Another set of rats was subjected to the same corneal implantation procedure, and two widely accepted indicators of neovascularization, microvessel counts and vascular endothelial growth factor expression, were assessed at Days 3, 5, 7, and 9 after surgery. The tissue-group results for grade of angiogenic activity, microvessel count, and grade of vascular endothelial growth factor expression were compared.

RESULTS

Of the three CVM types, the AVMs showed the highest angiogenic activity, cavernous malformations exhibited some degree of angiogenic activity (less than AVMs but more than normal brain artery tissue), and angiogenesis induction by venous angiomas was comparable to that of normal brain artery tissue. Corneas implanted with the AVM samples showed Grade 1 angiogenesis on Day 2, Grade 2 angiogenesis on Day 4, and Grade 2.5 angiogenesis on Day 8. Cavernous malformation samples caused Grade 1 angiogenesis after Day 5, and grading remained less than 1.5. Venous angioma samples resulted in angiogenesis graded less than 1.

CONCLUSION

The results showed that this rat model of corneal angiogenesis is of value for assessing the angiogenic potential of CVMs and for evaluating details of the neovascularization process over time. Further investigation of CVMs with this model might yield information about how angiogenesis can be modulated, and this could lead to development of biological treatments that inhibit this process.

Interleukin-1alpha production in human corneal scars

We studied IL-1alpha level in corneal scars with/without neo-vascularization. A total of 27 patients underwent grafting for corneal scar. Recipients were grouped according to number of vascularized quadrants (0 to IV/IV): none (n = 12), one (n = 5), two (n = 4) and four (n = 6). Recipient corneas were collected during surgery and IL-1alpha measured by immunoassay. Controls were donor corneas unsuitable for transplantation. Graft rejection rate was calculated for each group. Mean IL-1alpha concentration in corneal scars was 6 +/- 3.93 pg/mm3; significantly higher as compared to controls (1.25 +/- 2.03 pg/mm3). IL-1alpha correlated well with amount of blood vessels, except in IV/IV scars: 5.17 +/- 3.65 pg/mm3 for 0/IV; 8.02 +/- 2.51 pg/mm3 for I/IV; 8.27 +/- 3.62 pg/mm3 for II/IV and 4.47 +/- 5.03 pg/mm3 for IV/IV corneal scars. Vascularization of corneal scar is associated with increased IL-1alpha level (in all but highly vascularized scars), indicating that IL-1alpha promotes early stages of vascularization. Graft rejection rate increases in patients with higher vascularization, independently of IL-1alpha level.

Characterization of corneal pannus removed from patients with total limbal stem cell deficiency

PURPOSE

To determine the epithelial lineage of origin in corneal pannus tissue surgically removed from patients with total limbal stem cell (SC) deficiency.

METHODS

The lineage of origin of the entire conjunctivalized pannus removed from eight corneas with a diagnosis of total limbal SC deficiency was characterized by anti-keratin (K)-3 and anti-K19 monoclonal antibodies. The protein and mRNA of epithelial outgrowth from segments of five such pannus specimens were analyzed by Western blot and reverse transcription-polymerase chain reaction, respectively.

RESULTS

Cross sections of all eight specimens showed a stratified epithelium with goblet cells expressing mucin (MUC)-5AC, and a stroma showing blood vessels and inflammatory cell infiltrates. Immunostaining showed full-thickness expression of K19 in the entire pannus of all eight specimens. Expression of K3 was negative in seven patients, but was sporadically positive in a patient with Stevens-Johnson syndrome. In culture, all five pannus specimens generated a compact, small epithelial cell outgrowth, and except for one, reached confluence in 2 to 3 weeks. The K3/K12 pair was expressed by extracts of cell outgrowth from the control limbal epithelial explant, but not in all five pannus specimens. A 60-kDa band of DeltaNp63 was expressed in the control specimen and in all five pannus specimens. Cell outgrowth expressed K3 transcript in three, but none showed K12 transcript.

CONCLUSIONS

The resultant epithelial phenotype of the pannus tissue was not corneal, as evidenced by the negative staining to cornea-specific K12 mRNA and protein, but was conjunctival, as evidenced by the presence of goblet cells, the weak expression of K3, and the strong expression of K19. The abundant expression of DeltaNp63 in such conjunctiva-derived epithelium in eyes with total limbal SC deficiency raises doubts as to its validity as a limbal SC marker.

Application of femtosecond ultrashort pulse laser to photodynamic therapy mediated by indocyanine green

BACKGROUND/AIMS

To evaluate treatment with high peak power pulse energy by femtosecond ultrashort pulse laser (titanium sapphire laser) delivered at an 800 nm wavelength for corneal neovascularisation using photodynamic therapy (PDT) mediated by indocyanine green (ICG).

METHODS

Using a gelatin solid as an in vitro corneal model, the safety of laser power was studied to determine if it degenerated gelatin with or without ICG. The authors then induced corneal neovascularisation in rabbit eyes by an intracorneal suturing technique. Fluorescein angiography was used to evaluate occlusion before PDT and 0, 1, 3, and 10 days after PDT. The authors performed light microscopy with haematoxylin eosin staining and transmission electron microscopy to determine thrombosis formation in the neovascular regions.

RESULTS

The threshold of peak laser power density ranged from 39 to 53 W/cm(2). Laser irradiation was started 30 seconds after a 10 mg/kg ICG injection, and all irradiated segments were occluded at 0, 1, 3, and 10 days at 3.8 J/cm(2). Light and electron microscopy documented thrombosis formation in the neovascular region.

CONCLUSION

Femtosecond pulse laser enhanced by ICG can be used for PDT. Because of effective closure of corneal neovascularisation at a low energy level, the high peak power pulse energy of the femtosecond pulse laser might be more efficacious than continuous wave laser for use with PDT.

Free Autologous Buccal Mucosal Graft Transplantation to Treat Ocular Complications after Toxic Epidermal Necrolysis: Case Report

BACKGROUND

Toxic epidermal necrolysis (TEN) can lead to ocular surface scarring associated with pain, dry eye symptoms, and decreased visual acuity that often are difficult to treat.

HISTORY AND SIGNS

A 34-year-old woman was referred to our department two-years after TEN induced by lamotrigin (lamictal(R)). She was complaining of severe visual acuity loss, pain, and dry eye symptoms. Visual acuity was reduced to light perception in the right eye (RE) and to 0.2 in left eye (LE). Basal Schirmer test was 2 mm in RE and 3 mm in LE. With or without therapeutic contact lenses, the patient was experiencing severe discomfort requiring tear supplementation up to 50 - 80 times/day in both eyes.

THERAPY AND OUTCOME

A free autologous mucosal graft (3.5 x 2.0 cm) was transplanted from the lower lip into the upper RE fornix. Six months after surgery, with therapeutic contact lenses, the need for tear supplementation was markedly reduced to 3 - 4 times/day in RE while it remained unchanged in LE. In RE, slit-lamp examination revealed decreases in the corneal stromal edema and in the diameter of neo-vessels associated with an improvement of visual acuity (counting fingers at 30 cm). Basal Schirmer test values were unchanged. It has to be mentioned that the improvement observed after surgery was markedly dependent on wearing a therapeutic contact lens.

CONCLUSIONS

Free autologous buccal graft transplantation (with its presumably accessory salivary glands) in association with the use of a therapeutic contact lens can be an efficient approach to treat ocular complication following drug-induced TEN (Lyell's syndrome).

Fluorescein angiographic monitoring of corneal vascularization in lipid keratopathy

The use of digital fluorescein corneal angiography to assist argon laser photocoagulation is reported. Photocoagulation was performed on the vascular supply of lipid keratopathy in the left eye of a 44-year-old woman.

Fluorescein-potentiated argon laser therapy improves symptoms and appearance of corneal neovascularization

PURPOSE

To evaluate patients' self-assessment of their symptoms and cosmetic appearance after fluorescein-potentiated argon laser treatment (FPAL) for corneal inflammation associated with neovascularization. To describe the objective effects of FPAL therapy on established corneal neovascularization with secondary corneal edema and lipid keratopathy.

METHODS

Fifteen patients with corneal neovascularization resulting from various infectious and traumatic etiologies were enrolled in an open, nonrandomized pilot study. Treatment consisted of repeated sessions of intravenous fluorescein, a photosensitizer, combined with blue-green argon laser applications to abnormal corneal vessels. Patients completed a written survey to grade their symptoms and cosmetic appearance prior to treatment and at the end of the follow-up period. Objective changes in signs after FPAL treatment were described by two nonmasked ophthalmologists after slit-lamp examinations and review of serial corneal photographs.

RESULTS

Clinical symptoms of blurred vision (p <or= 0.003), photophobia (p <or= 0.03), and cosmetic appearance ( p <or= 0.02) were found to be significantly improved by the patient's subjective assessment survey. There was a trend toward pain reduction (p <or= 0.06) but no apparent reduction in tearing or foreign body sensation (p <or= ns). Objective signs of corneal edema, neovascularization, and lipid keratopathy appeared to be reduced after FPAL therapy.

CONCLUSION

FPAL therapy for corneal neovascularization, edema, and lipid keratopathy resulted in a significant reduction in symptoms and improved quality of life for 14 of 15 (93%) patients. A controlled clinical trial to confirm the reported improvement in signs observed in this pilot study should be considered.

Frequency doubled Nd:YAG (532 nm) laser photocoagulation in corneal vascularisation: efficacy and time sequenced changes

PURPOSE

To evaluate the efficacy of frequency-doubled Nd:YAG (532 nm) laser treatment in quiescent corneal vascularisation, and to record the sequential changes in lasered vessels and complications in eyes with one and two quadrant vascularisation.

METHODS

Thirty eyes (30 patients)--15 eyes (15 patients) with one-quadrant and 15 eyes (15 patients) with two-quadrant corneal vascularisation were treated. Frequency-doubled Nd:YAG laser (532 nm) was used at laser setting of 120-480 mw power, 50-150 mm spot size and 0.05 sec pulse duration. The area of corneal vascularisation, status of treated corneal vessels, area of corneal opacity and visual acuity were recorded before treatment, at one week after treatment and thereafter at monthly intervals up to three months.

RESULTS

The mean area of corneal vascularisation decreased from 20.09% to 8.31% of the total corneal area in group I (p<0.01) and from 44.34% to 20.67% of the total corneal area in group II (p<0.01) at 3 months' follow-up. The mean reduction in the area of corneal vascularisation was 58.64% in group I and 53.38% in group II (p>0.05). Of 148 corneal vessels treated, 60 (44.6%) were totally occluded, 44 (30%) partially occluded, 37 (28%) recanalized and there was one shunt vessel at one week following laser treatment. At three months' follow-up, 80 (54.15%) vessels were totally occluded, 14 (9%) partially occluded, 52 (35.14%) recanalised and two shunt vessels appeared. Thus, at three months' follow-up, the number of totally occluded vessels increased and partially occluded vessels decreased. Superficial corneal haemorrhage was observed in 4 (14%) patients.

CONCLUSION

Frequency-doubled Nd:YAG (532 nm) laser photocoagulation appears a safe and effective means of reducing the area of corneal vascularisation in quiescent eyes with vascularised corneal opacities.

A case of atypical Cogan's syndrome with uncommon corneal findings

PURPOSE

We report a case of atypical bilateral interstitial keratitis associated with Cogan's syndrome.

METHODS

A 28-year-old man presented with a 2-year history of recurrent bilateral keratitis. Bilateral hearing loss preceded the ocular symptoms by 2 years. The patient also complained of skin nodules, headache, back pain, and arthritis. Corneal finding were consistent with superior stromal keratitis with stromal neovascularization and lipid deposition in the stroma. The patient's audiogram revealed cochlear pathology compatible with Cogan's syndrome (sensorineural deafness).

RESULTS

The patient was treated with topical steroids but eventually required corneal transplantation in the right eye as a consequence of progressive loss of vision secondary to progressive lipid keratopathy. Visual acuity at the patient's most recent follow-up evaluation was 20/40.

CONCLUSION

This case represents an unusual type of interstitial keratitis associated with Cogan's disease. The absence of ocular symptoms at the time of initial ear involvement and the atypical presentation of the keratitis were responsible for the delay in diagnosis in this patient, resulting in hearing impairment.

Cytotoxic T cells play no essential role in acute rejection of orthotopic corneal allografts in mice

PURPOSE

To determine whether cytotoxic T cells of the direct alloreactive type are activated and responsible for early, acute failure of orthotopic corneal allografts observed in eyes of C57BL/6 but not of BALB/c mice.

METHODS

Corneas from BALB/c and BALB.B mice were placed orthotopically in eyes of C57BL/6 and beta-2 microglobulin knockout mice (deficient in CD8(+) cytotoxic T cells). Graft fates were assessed clinically, and the T lymphocytes of recipients were assayed for the capacity to lyse target cells bearing donor major (MHC) and/or minor histocompatibility (minor H) antigens (direct and indirect pathways, respectively). RESULTS. Similar to BALB/c recipients, C57BL/6 mice with rejected cornea allografts acquired donor minor H-specific T cells. Unlike BALB/c recipients, C57BL/6 mice-both rejectors and acceptors-acquired donor MHC-specific T cells. beta-2 Microglobulin knockout mice showed rejection of corneal allografts in a manner indistinguishable from C57BL/6 mice, including early, acute rejection, yet T cells from beta-2 microglobulin knockout recipients of corneal allografts displayed no cytotoxic T cells specific for either donor MHC or minor H alloantigens.

CONCLUSIONS

Although C57BL/6 mice acquired donor MHC-specific cytotoxic T cells (direct alloreactive cells), neither these cells nor donor minor H-specific cytotoxic T cells (indirect alloreactive cells) play any essential role in corneal allograft rejection, including the early acute failure uniquely observed in C57BL/6 eyes.

Complications with one-piece lamellar keratolimbal grafts for simultaneous limbal and corneal pathologies

PURPOSE

To determine the efficacy of a one-piece lamellar keratolimbal graft for the treatment of ocular surface disorders involving the limbus and cornea.

METHODS

A retrospective study of a case series including eight patients with either Stevens-Johnson syndrome (four patients), ocular cicatricial pemphigoid (three patients), or familial subepithelial amyloidosis of the cornea (one case) was performed with a mean follow-up period of 18 months after surgery.

RESULTS

Of the eight cases, three patients retained a corneal epithelial appearance upon their latest visit. No statistically significant difference was observed between preoperative visual acuity (0.013) and postoperative acuity (0.082). Stromal neovascularization was observed in all cases. Seven of eight cases experienced persistent epithelial defects (PED), four of which evolved secondary infectious ulcers. Two cases required further surgical intervention to treat PED or infectious ulcers. None of the cases developed glaucoma.

CONCLUSION

A one-piece keratolimbal graft does not seem to offer any advantage over a two-piece limbal and corneal graft in the treatment of severe ocular surface disorders involving the limbus and cornea.

Immunohistochemical localization of vascular endothelial growth factor, transforming growth factor alpha, and transforming growth factor beta1 in human corneas with neovascularization

PURPOSE

To analyze presence and distribution of vascular endothelial growth factor (VEGF), transforming growth factor (TGF)alpha, and TGFbeta1 in human corneas with neovascularization due to different corneal diseases.

METHODS

Indirect immunohistochemistry for VEGF, TGFalpha, and TGFbeta1, was performed on paraffin-embedded corneas obtained by keratoplasty. Corneas from each of the four main groups of histopathologic diagnoses associated with corneal neovascularization were analyzed (scarring after keratitis, graft rejection/insufficiency, acute necrotizing keratitis, scarring after mechanical/chemical injury). Subclassification of inflammatory infiltrates was done using immunohistochemistry for CD3 (T-lymphocytes) and CD68 (macrophages).

RESULTS

The analyzed angiogenic factors were detectable in corneas from all four histopathologic groups in a similar distribution; capillary endothelial cells, stromal and intravascular inflammatory cells (T-lymphocytes, macrophages), and basal corneal epithelial cells stained positive for the tested angiogenic factors.

CONCLUSION

The angiogenic factors VEGF, TGFalpha, and TGFbeta1 are detectable in human corneas with neovascularization. Their distribution is quite uniform in different corneal diseases, resulting in corneal angiogenesis. An antiangiogenic therapy inhibiting corneal neovascularization by antagonizing angiogenic factors would have to counteract several angiogenic factors.

Angiogenesis in corneal diseases: histopathologic evaluation of 254 human corneal buttons with neovascularization

PURPOSE

Angiogenesis in corneal diseases can necessitate corneal transplantation and induce graft rejection. The aim of this study was to find out the histopathologic prevalence of angiogenesis in human corneas removed during keratoplasty, to establish the histopathologic diagnoses most commonly associated with angiogenesis, and to evaluate the anatomic location of new corneal vessels.

METHODS

Corneal buttons (2,557) after keratoplasty were sent to and analyzed in our ophthalmopathology laboratory between 1992 and 1996. Of these, 1,278 full-thickness and lamellar corneal buttons were randomly retrieved and evaluated in this study.

RESULTS

Of 1,278 human corneal buttons obtained by keratoplasty, 254 (19.9%) showed angiogenesis. Associated histopathologic diagnoses were (a) scarring after keratitis (109, 45.4%); (b) graft rejection and insufficiency (73, 30.4%); (c) acute necrotizing ulcerative keratitis (30, 12.5%); and (d) scarring after mechanical or chemical injuries (28, 11.7%). Histopathologically, new vessels were usually associated with corneal edema or inflammatory cells or both (76%). The most common locations of new vessels were the upper and middle third of the corneal stroma. Only 11% of new vessels were located solely in the deep stromal layers.

CONCLUSION

Angiogenesis is a common histopathologic feature of corneal diseases leading to corneal transplantation and was found in 19.9% of excised human corneal buttons. Systemic or topical antiangiogenic therapy could reduce the need for corneal transplantation and retransplantation.

Induction of donor-specific ACAID can prolong orthotopic corneal allograft survival in "high-risk" eyes

PURPOSE

To examine the effect of donor-specific anterior chamber-associated immune deviation (ACAID) induction on the survival of orthotopic corneal allografts in neovascularized graft beds.

METHODS

To induce donor-specific ACAID in recipients, peritoneal exudate cells (PEC) from C57BL/6 mice were incubated overnight with transforming growth factor (TGF)-beta. Cultured PEC were injected intravenously (i.v.) into BALB/c mice, and, 1 week later, these animals received orthotopic corneal allografts from C57BL/6 donors into neovascularized graft beds. Control mice received i.v. injection of syngeneic (BALB/c) PEC, cultured overnight with TGF-beta, and then received orthotopic corneal allografts from C57BL/6 donors.

RESULTS

All corneal allografts (15 out of 15) were rejected within 2 weeks after grafting in the neovascularized graft beds of control animals. However, only 6 out of 16 (37.5%) of corneal allografts were rejected in recipients in which donor-specific ACAID had been induced by injection of allogeneic PEC cultured with TGF-beta.

CONCLUSION

Previous studies revealed that rejection of orthotopic corneal allografts in neovascularized graft beds in mice correlated with acquisition of donor-specific delayed hypersensitivity (DH). The results of this study suggest that induction of donor-specific ACAID, which selectively impairs DH responses to donor antigens, effectively prolongs corneal allograft survival in "high-risk" eyes.

[A preliminary report of epikeratophakia for the treatment of Terrien's degeneration]

PURPOSE

To evaluate the efficacy of epikeratophakia for the treatment of severe Terrien's degeneration.

METHODS

Four eyes with severe Terrien's corneal degeneration are studied. The lesions were located at the peripheral cornea and the corneal thickness was less then 1/3 of normal. Plano keratoplasty was performed. A lamellar lenticule with a 2 mm scleral rim was grafted on the cornea of which the epithelium had been removed. Keratometry and cycloplegic refraction were performed pre- and post-operatively.

RESULTS

Follow-up was between 3 and 13 months (mean, 10 months). All grafts remain clear. The properative mean cylinder was 11.5 diopters and the postoperative mean cylinder was 3.9 diopters. Best corrected visual acuity was improved in 3 eyes. Interface opacification is the main complication, like other forms of epikeratoplasty. Epithelial ingrowth occurred in one eye and the lenticule was replaced.

CONCLUSIONS

Epikeratophakia is a simple and effective way for the treatment of severe Terrien's degeneration. This procedure not only increases the corneal thickness, but also hepls the cornea to preserve its transparency, since the Bowman's layer remains intact.

[A study of corneal transplantation and human leukocyte antigen matching]

OBJECTIVE

The effect of human leukocyte antigen (HLA) matching on immune rejection after keratoplasty was studied.

METHODS

Immunoserologic HLA typing was performed on thirty-three eyes with corneal vascularization of 33 high-risk patients before keratoplasty, and HLA matching was made before the surgery. The donor corneas used for these cases were selected on the basis of obtaining a negative HLA cross-match test and matched ABO antigen compatibility of blood group before surgery. The mean follow-up was fifteen months.

RESULTS

The findings suggested that there should be highly statistic significance (t = 7.36, P < 0.01) between the rate of rejection of well matched group and that of the poorly matched one. There was no correlation between the number of HLA antigen matched and the rejection rate (t = 0.917, P > 0.05).

CONCLUSION

Lower incidence of corneal graft failure from allograft rejection occurs when well HLA matching is used for selecting donor in high-risk patients with corneal vascularization.

Fate of orthotopic corneal allografts in eyes that cannot support anterior chamber-associated immune deviation induction

PURPOSE

Corneal allografts placed in human eyes at high risk often fail, and immune rejection is thought to be a major pathogenic factor. To understand the immunologic factors responsible for rejection in this instance, the authors have created "high-risk" eyes in mice by inducing corneal neovascularization. The authors then examined the fate of orthotopic corneal grafts placed in these beds and assessed the development of donor-specific delayed hypersensitivity (DH) in recipient mice.

METHODS

Three interrupted sutures were placed in the central cornea of recipient BALB/c mice to induce corneal neovascularization. Two weeks later, when corneal vessels occupied more than two quadrants of the cornea, mice received orthotopic corneal grafts from donor mice expressing alloantigens encoded by major and minor histocompatibility loci. Corneal allografts were evaluated by slit-lamp examination after grafting, and recipient mice were examined at the time of the rejection to determine whether they had acquired DH to alloantigens expressed on the corneal grafts.

RESULTS

Compared to grafts placed in normal eyes, a much higher incidence of rejection was observed among corneal allografts placed in neovascularized eyes (96.7% versus 46.7%). Moreover, grafts in neovascularized beds were rejected much more swiftly (2 weeks versus > 3 to 4 weeks). Rejection of corneal allografts in high-risk eyes coincided temporally with development of intense donor-specific DH, and the specificity of this immune response was directed solely at minor H antigens (not major histocompatibility complex-encoded antigens) on the graft.

CONCLUSIONS

These results indicate that eyes rendered high risk by virtue of corneal neovascularization fail to provide immune privilege for orthotopic corneal allografts. In this circumstance, the grafts rapidly induce intense donor-specific DH that is readily detectable within 2 weeks of engraftment, at which time the grafts are acutely and universally rejected. The recipient DH response is directed exclusively at minor H antigens on the graft, which is consistent with the view that neovascularization creates graft beds in which recipient antigen-presenting cells infiltrate the graft and carry antigenic information by lymphatics to draining lymph nodes. In this manner, anterior chamber-associated immune deviation is avoided, and potentially allodestructive DH is promoted.

Confocal microscopy of corneal graft rejection

Corneal allografts were transplanted into inflamed and vascularized graft beds in rabbit eyes. The grafts were examined every 4 days by slit-lamp biomicroscopy and scanning confocal microscopy. Confocal images were recorded with a video camera and computer enhanced in real-time. Layers of the cornea were visualized in serial optical sections parallel to the epithelium. In the third postoperative week, signs of graft rejection were observed; slit-lamp examination revealed a circumferential line of epithelial rejection, along with cloudiness and edema. Vessels were observed growing into the graft. By confocal microscopy, infiltrating cells were seen in the graft stroma. Foci of cells were especially pronounced around the sutures. Scattered leukocyte infiltrates were prominent at capillary terminals. There was an accompanying reduction in the stromal keratocyte density in the region of the infiltrate. Additionally, various degrees of fibrosis were noted around each suture and at the host-graft interface. Confocal microscopy may provide a valuable clinical tool for determining the earliest indicators of an antigraft immune response, and as an aid in the differential diagnosis of other inflammatory conditions of the cornea.

[Complex anterior chamber dysgenesis with bilateral corneal ectasia]

BACKGROUND

Sclerocornea is a congenital, uni- or bilateral, non-progressive, non-inflammatory malformation characterized by histological changes of the cornea resembling scleral tissue.

CASE REPORT

We report the case of a 2-month-old child with bilateral dysplasia of the anterior segment including: 1. extreme corneal ectasia; 2. vascularized, opacified microcornea; 3. presence of rudimental limbus; 4. anterior scleral dysplasia. The axial length measured by means of ultrasonography (A-scan) was about 24 mm in both eyes. A penetrating keratoplasty was first performed in the right eye and one week later in the left eye. Intraoperatively an advanced iris atrophy with extensive anterior synechiae, as well as a localized anterior subcapsular cataract were seen bilaterally. A pale optic disk with a maximally enlarged optic cup could be seen only in the left eye.

CONCLUSION

Although the histologic examination was compatible with the diagnosis of sclerocornea, the presence of atypical clinical findings previously unreported does not allow a definite classification of the case reported herein.

The effects on inhibition of corneal neovascularization after human amniotic membrane transplantation in severely damaged rabbit corneas

Human amniotic membrane isolated from the placenta contained basement membrane components such as type IV collagen, laminin, and 6 and 4 integrins, all of which remained detectable while preserved in glycerin for one week. One month after the n-heptanol removal of the total corneal epithelium and the limbal lamellar keratectomy, all rabbit eyes carried features of limbal deficiency, including conjunctival epithelial ingrowth, vascularization and chronic inflammation. Ten control eyes then received a total keratectomy, and 13 experimental eyes received an additional amniotic membrane transplantation. Three-month follow-ups revealed that all control corneas were revascularized to the center with granuloma and retained a conjunctival phenotype. In contrast, in the experimental groups, 5 corneas became clear with either minimal or no vascularization; the rest had either mild peripheral (5) or total (3) vascularization and more cloudy stroma. Using monoclonal antibodies for epithelial markers and matrix components, we concluded that the success correlated with the return of a cornea-like epithelial phenotype and the preservation of the amniotic membrane, whereas the failure maintained a conjunctival epithelial phenotype and the amniotic membrane was either partially degraded or covered by host fibrovascular stroma. Measures taken to facilitate the former might prove this procedure clinically useful for ocular surface reconstruction.

Comparison of Yellow Dye, Continuous Wave Nd=YAG, and Argon Green Laser on Experimentally Induced Corneal Neovascularization

BACKGROUND

Corneal neovascularization is generally undesirable because it can lead to corneal scarring, lipid deposits, and corneal graft failure. To eliminate these vessels, several techniques are available including laser photocoagulation.

METHODS

This prospective study was designed to compare the effectiveness of three laser wavelengths (continuous wave Nd:YAG, 1064 nm; argon green 514 nm; and yellow dye, 570 nm) to obliterate experimentally induced corneal neovascularization in the rabbit. Corneal vascularization was created in 12 rabbits by placing 7-0 silk sutures through two quadrants of the cornea. Once neovascularization was complete, the suture was removed and one of the three lasers was applied to occlude vessels at one of the neovascular sites. The other site was used as a control.

RESULTS

The yellow wavelength, when compared with the green required fewer exposures to occlude corneal vessels. At no time during observation was any laser more effective than the control. In the continuous wave Nd:YAG group, tissue necrosis was needed to achieve closure of vessels.

CONCLUSIONS

Yellow and green laser light are equally effective in eliminating the corneal vessels. Continuous wave Nd:YAG, as used here, appears to be a poor choice.

Effects of laser photocoagulation on corneal neovascularization in rabbits

BACKGROUND

Corneal neovascularization is a common clinical entity. Although visual acuity is usually impaired and corneal function compromised, there has been only limited success in the clinical management of this condition. We evaluated the efficacy of laser photocoagulation of neovascularization in the rabbit cornea.

METHODS

New vessel formation was provoked by the placement of sutures in the corneas. Rose bengal was injected intravenously and new vessels in the upper part of the corneas were treated with an argon laser. The lower halves were used as controls. Eighteen rabbits were divided into 2 groups. In group A neovascularization was treated 28 days after suture removal, when corneal inflammation had regressed. In group B treatment was performed 3 days after suture removal, when the cornea still exhibited marked inflammation. Postoperatively, the corneas were studied by slit-lamp microscopy, fluorescein angiography, and light, as well as electron microscopy.

RESULTS

In group A, treatment led to the immediate occlusion of the vessels and to their gradual disappearance during the course of 3 months. In group B, no occlusion was seen during the 3-month follow-up period. The main histologic findings in the occluded vessels were endothelial cell disruption and degeneration, and the formation of clots.

CONCLUSION

Our results suggest that argon laser photocoagulation using rose bengal is an effective method of occluding corneal new vessels, providing there is no corneal inflammation at the time of treatment.

Suppression of corneal allograft rejection by systemic cyclosporine-A in heavily vascularized rabbit corneas following alkali burns

Immunologic rejection is the main cause of corneal graft failure, especially in vascularized corneal beds. The purpose of this study was to investigate the effect of systemic Cyclosporine-A (CsA) on the survival of corneal allografts in heavily vascularized rabbit corneal beds, following alkali burn. Heavy corneal vascularization was induced in one eye of 20 rabbits by alkali burn. Forty-five days later, penetrating keratoplasty was performed in all the heavily vascularized corneas. Twenty-five mg/kg/day of CsA was intramuscularly administered to 10 rabbits for 30 days. The other 10 rabbits were treated with the solvent without CsA and were used as a matched control group. The results show a significant difference in corneal allograft survival between the two groups. All corneal grafts in the untreated group were intensely rejected and vascularized within 3 weeks. Nine of the 10 corneal transplants, in the CsA-treated group, remained transparent without signs of immunologic rejection for > 180 days. In one corneal transplant, minor signs of rejection occurred. We suggest that CsA, when given systemically, is a potent drug in the prevention of immunologic rejection in high-risk corneal transplantations, such as allografts, in heavily vascularized corneas following alkali burn.

Mixed lymphocyte culture responses in rabbits undergoing corneal grafting and topical cyclosporine treatment

Using a vascularized cornea rabbit model closely resembling human high-risk keratoplasty, corneal allografts were performed on three groups of animals that were paired and tested preoperatively by mixed lymphocyte cultures (MLCs). The three groups were group A, unmodified controls with clear corneas; group B, untreated animals with vascularized corneas; and group C, animals treated with topical cyclosporine (CSA) with vascularized corneas. The MLC results were expressed as stimulation indices (SIs) and divided into low (SI < or = 20) and high (SI > 20) responders and were correlated with final outcome of grafts using survival analysis estimates. In group A, five of 13 (38.5%) grafts rejected, the chance of failure depending on the degree of MLC mismatch between donor and recipient (p = 0.02). All allografts in group B rejected regardless of the degree of mismatch. In group C, seven of 12 (58.3%) grafts rejected, indicating that topical CSA significantly improved survival (p = 0.003) compared with group B. Grafts with mild degrees of MLC mismatch (low responders) survived better (p = 0.0003) than did higher degrees of MLC mismatch (high responders), all of which rejected despite treatment. Our results indicate that both corneal vascularization and the degree of donor-recipient matching play important roles in determining corneal graft survival.

Hemorrhage complicating YAG laser feeder vessel coagulation of cornea vascularization

A neodymium:yttrium-aluminum-garnet (Nd:YAG) laser was used in the thermal mode to coagulate blood vessels in a patient with a vascularized corneal leukoma in an attempt to reduce neovascularization before penetrating keratoplasty. Occlusion of the feeder artery at the periphery was followed by a large stromal hemorrhage. A successful keratoplasty was performed 2 days later.

[Obliteration of vessels growing into the cornea with the help of laser energy]

The vessels proliferating into cornea cause epithelium biotransformation and lipid keratopathy, decreasing corneal transparency. In 9 patients (10 eyes) argon laser obliteration of these vessels was performed. In 8 eyes improvement of corneal transparency and visual acuity was achieved, in other two the neovascularization was restrained. The best results were observed in lipid keratopathy.

Treatment of corneal neovascularization with argon laser

Corneal neovascularization, which is associated with complications in corneal diseases, can cause lipid deposit, decreasing vision, and graft rejection after penetrating keratoplasty (PKP). Corneal laser photocoagulation using an argon laser or yellow dye laser for ablation of corneal neovascularization has been described. We performed corneal argon laser photocoagulation (CALP) in two male patients with corneal neovascularization after herpetic keratitis. One PKP was performed after CALP and restored good vision with no rejection of the graft during an 8 month follow-up period. In the other case we observed visual improvement and no recurrence of corneal neovascularization after CALP.

Biomicroscopic and histopathologic observations after corneal laser photocoagulation in a rabbit model of corneal neovascularization

Corneal neovascularization complicates many anterior segment diseases. Corneal laser photocoagulation using yellow light (577 nm) has been shown to reduce corneal neovascularization. No histopathologic studies of the effects of this treatment on the eye have been reported, however. Target (cornea) and nontarget (iris, lens, retina, and choroid) ocular tissue were studied 1, 24, and 48 h and 5 days after yellow dye corneal laser photocoagulation in a rabbit model of corneal neovascularization. Biomicroscopic examination of the corneas revealed intracorneal hemorrhage in five of 24 (21%) eyes of nonpigmented rabbits. Faint lenticular opacities were observed in two eyes of pigmented rabbits 24 h after laser treatment. Histopathologic examination revealed increased cellularity (neutrophils) (p < 0.005) in the cornea, increasing from 1 h after treatment, peaking 24 h later, and persisting past 5 days. Distortion of the corneal lamellae by red blood cells occurred in eyes in which intracorneal hemorrhage developed. These results indicate that corneal laser photocoagulation using yellow light is a relatively safe procedure for reducing corneal neovascularization.

Laser photocoagulation of experimental corneal stromal vascularization. Efficacy and histopathology

BACKGROUND

Conventional treatment of corneal stromal vascularization is often inadequate. The authors developed a rabbit model of corneal stromal vascularization, treated it with laser photocoagulation, and then studied the histopathology.

METHODS

A reproducible model of corneal stromal vascularization was developed in albino rabbits by injecting sodium hydroxide into the corneal stroma. Corneal stromal vascularization was produced in both eyes of 13 rabbits, and treated after stabilization at 5 weeks with 577-nm yellow dye laser in 1 eye of each rabbit. Seven rabbits were followed for 6 months with corneal angiography and photography, and the corneal stromal vascularization quantified with a grid. The other 6 rabbits were killed at 1, 4, 8, 24, 48 hours, and 6 days after laser photocoagulation and examined by light and transmission electron microscopy.

RESULTS

Stable corneal stromal vascularization was observed in the anterior and midstroma for at least 6 months in the model. Laser photocoagulation reduced corneal stromal vascularization significantly compared with the controls (P < or = 0.05), resulting in 40.7% +/- 5.0%, 45.3% +/- 3.3%, and 34.9% +/- 5.2% (mean +/- standard error of the mean) reduction at 2, 4, and 6 months, respectively. Maximum inflammatory cell infiltrates were detected at 8 hours after laser photocoagulation, which diminished markedly at 6 days. The stroma of unlasered eyes showed no inflammatory cells and considerably more patent blood vessels than the lasered eyes. In the lasered eyes, transmission electron microscopy showed damaged vascular endothelial cells, extravasated erythrocytes, haphazardly arranged collagen fibrils, thrombus formation, and ghost vessels in the stroma. No damage was observed in the deep corneal stroma or endothelium in the lasered eyes.

CONCLUSION

Laser photocoagulation is effective in reducing corneal stromal vascularization in this model for at least 6 months. It does not damage the deeper stroma or endothelium.

[Analysis of penetrating corneal regrafting in 29 cases]

Repeated penetrating keratoplasty was retrospectively analyzed in 29 cases followed up 1-4 years postoperatively. The regraft remained clear in 10 eyes (34.5%). The major causes of regrafting failure were similar to those of the initial keratoplasty, i.e. immunologic rejection, postoperative angle-closure glaucoma, and donor graft failure.

Corneal laser photocoagulation for treatment of neovascularization. Efficacy of 577 nm yellow dye laser

The authors treated corneal neovascularization in 25 eyes of 23 patients with corneal laser photocoagulation using 577 nm yellow light. Four groups of patients were treated: patients with corneal neovascularization and active graft rejection (group 1); patients with neovascularization before penetrating keratoplasty (PK) (group 2); lipid keratopathy patients with opacification and/or focal edema threatening the visual axis (group 3); and patients with extensive corneal neovascularization, who were not candidates for PK (group 4). Area of neovascularization and clinical outcome were monitored. After corneal laser photocoagulation, there was a statistically significant reduction in the neovascularized area in group 1 from 32% of corneal area to 10%, and in group 3 from 46% to 27%. All five patients in group 1 had resolution of their graft rejection. In group 3, there was a reduction in the area of corneal opacification from 59% of corneal area to 52%. This difference was not statistically significant. Seven of nine patients in group 3 had stabilization or improvement in their vision over a mean of 9.3 months follow-up. There was no significant change in neovascularized area in groups 2 and 4. In group 2, no rejection reactions occurred over a mean of 5.6 months follow-up after PK. In group 4, corneal laser photocoagulation was disappointing.

Laser photocoagulation for corneal stromal vascularization

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