Recurrence of the clinical signs of lattice corneal dystrophy (type I) in corneal transplants

Classic lattice corneal dystrophy: a brief review and summary of treatment modalities

PURPOSE

To provide a brief summary and comparison of the most recent literature on available and theorized treatment modalities for classic lattice corneal dystrophy (LCD). This paper aims to support practitioners in their management of this disease.

METHODS

A search was carried out on available literature through PubMed and Google Scholar of English language articles up to January 2023 that relate to the treatment of LCD. Due to scarcity of literature regarding specific novel therapies for LCD, results from other corneal pathologies (granular corneal dystrophy, corneal scarring) are sometimes included for contrast, which is clearly denoted.

RESULTS

LCD is a slowly progressive disease that leads to recurrent epithelial corneal erosions, stromal haze, corneal opacification, substantial discomfort, and visual impairment. Due to its autosomal-dominant inheritance pattern, this disease can persist throughout ancestral lines and requires consistent treatment and follow-up. An optimal management plan is necessary to (1) prolong years of life with best achievable visual acuity; (2) treat painful recurrent corneal erosions as they occur; (3) ensure proper follow-up throughout the life of a patient, as well as monitor at-risk offspring; and (4) monitor efficacy of treatment.

CONCLUSIONS

This paper addresses (1) treatment for early disease including corneal epithelial debridement, photo therapeutic keratectomy (PTK), femtosecond laser-assisted lamellar keratectomy (FLK), and others; (2) treatment for late disease including full thickness keratoplasties and anterior lamellar keratoplasties; and (3) potential future treatment considerations including a wide variety of topical/systemic, genetic, and regenerative approaches.

Management of Stromal Corneal Dystrophies; Review of the Literature with a Focus on Phototherapeutic Keratectomy and Keratoplasty

Corneal dystrophies are a group of non-inflammatory inherited disorders of the cornea. This review considers treatment options for epithelial-stromal and stromal corneal dystrophies: namely Reis–Bücklers, Thiel–Behnke, lattice, Avellino, granular, macular and Schnyder corneal dystrophies. Where there is visual reduction, treatment options may include either phototherapeutic keratectomy (PTK) or corneal transplantation. Due to the anterior location of the deposits in Reis-Bücklers and Thiel–Behnke dystrophies, PTK is considered the treatment of choice. For lattice, Avellino, granular and macular corneal dystrophies, PTK provides temporary visual improvement; however, with recurrences, repeat PTK or a corneal transplant would be needed. For Schnyder dystrophy, should treatment be required, PTK may be the preferred option due to the potential for recurrence of the disease in corneal transplantation. This review discusses the literature and evidence base for the treatment of corneal dystrophies in terms of visual outcomes and recurrence rate.

Influence of graft vascularization on graft survival following homologous limbo-keratoplasty

PURPOSE

Limbo-keratoplasty enables visual improvement and limbal stem cell transplantation at the same. During follow-up, most grafts show vascularization of the limbus. However, it is unclear whether vascularization is harmful due to immunologic effects or helpful to nourish the limbal stem cells and is therefore necessary for a clear graft. The aim of our study is to analyze the influence of graft vascularization on graft survival following homologous limbo-keratoplasty.

METHODS

In this retrospective study, we assessed all consecutive limbo-keratoplasties performed in our hospital. All eyes with suitable photo-documentation were included and divided into two groups (limbal stem cell deficiency and corneal dystrophy). We categorized the grade of vascularization (0, 1, 2, 3, 3b) and analyzed clear graft survival, recurrence of the underlying disease and the endothelial cell density (ECD) with regard to the reason for the graft. Event rates were estimated with the Kaplan-Meier method.

RESULTS

A total of 79 eyes with limbal stem cell deficiency and 15 with corneal dystrophies were analyzed. A high degree of graft vascularization had a tendency for better graft survival in limbal stem cell deficiency, whereas in corneal dystrophies, grafts with no vascularization had preferable outcomes. Recurrence-free graft survival was only seen in grade 1 and 3 vascularization in corneal dystrophies.

CONCLUSION

Vascularization of the limbus seems to have an impact on the long-term outcome of limbo-keratoplasty. The effect seems to be favorable in limbal stem cell deficiency and on recurrence rates in corneal dystrophies. However, the latter might be overshadowed by an unfavorable immunologic effect in corneal dystrophies where the baseline immunologic risk profile is commonly more favorable than in limbal stem cell deficiency.

Recurrence and Visual Outcomes of Phototherapeutic Keratectomy in Lattice Corneal Dystrophy: A Cohort Study

PURPOSE

To evaluate recurrence and visual outcomes of phototherapeutic keratectomy (PTK) in lattice corneal dystrophy.

METHODS

Kaplan-Meier survival analyses were retrospectively performed. Recurrence was defined as central biomicroscopic findings of recurrence with decreased visual acuity: loss of at least two lines or visual acuity ≤ 20/40) at any time during the follow-up.

RESULTS

Twenty-two virgin eyes and 10 with previous keratoplasty (20 patients; 13 women and 7 men) were studied during a mean of 4.7 ± 3.5 years (range: 11 months to 18 years). One and 5 years after the first PTK (PTK1), 1 of 32 and 12 of 32 eyes, respectively, recurred. The cumulative probabilities of recurrence were 3%, 48%, and 89% in the whole sample at 1, 5, and 10 years, respectively. All cases in the virgin group and 8 eyes in the previous keratoplasty group improved their visual acuity. There were no significant differences in recurrence probability between groups (log-rank test; P = .86). A second PTK (PTK2) was performed in 15 of 32 eyes, with 6 postoperative recurrences recorded. The cumulative probabilities of recurrence in the whole sample were 18%, 30%, and 44% at 1, 3, and 5 years, respectively. Visual acuity improved in 11 of 13 eyes in the virgin group and 2 of 2 eyes in the previous keratoplasty group. Recurrence probability after PTK1 and PTK2 was similar in the whole sample (log-rank test; P = .637). Persistent graft edema after PTK1 in one eye was the only complication found.

CONCLUSIONS

PTK can be an effective, safe, and repeatable treatment to delay keratoplasty in symptomatic lattice corneal dystrophy. [J Refract Surg. 2022;38(1):43-49.].

Contact lens induced bacterial keratitis in LCD II: Management and multimodal imaging: a case report and review of literature

PURPOSE

To describe the management and multimodal imaging of lattice corneal dystrophy type II (LCD-II) complicated by an infectious keratitis due to a bandage contact lens and to review current literature.

OBSERVATION

A 50-year-old female was diagnosed with Meretoja's Syndrome by the triad of facial palsy, loose skin (cutix laxa), and stromal corneal dystrophy. At slit lamp, bilateral lattice corneal dystrophy (LCD) was characterized by multiple linear refractile lines and subepithelial fibrosis along with Neurotrophic keratitis Mackie grade I. Findings of anterior segment optical coherence tomography (AS-OCT) were epithelial irregularity, subepithelial fibrosis, hyperreflectivity on anterior stromal layer, lobulated stromal surface. In vivo confocal microscopy (IVCM) showed hyperreflected deposits on the basal and Bowman layers, visible keratocytes; fine lines and streaks between corneal lamella. The sub-basal nerve plexus and the stromal nerves were no longer visible. She presented in emergency with a left red eye. A severe bacterial keratitis was diagnosed as a complication of a bandage contact lens used to treat recurrent epithelial erosion. Corneal anesthesia was complete. Corneal neovascularization was evident 10 weeks later and topical bevacizumab (5 mg/ml) was introduced twice daily. Partial regression of deep stromal vessels was noticed at 3 months.

CONCLUSION

In Meretoja's syndrome, neurotrophic keratopathy secondary to polyneuropathy due to systemic amyloid deposits is present in the advanced stages, promotes recurrent corneal erosions. Corneal sensitivity test, AS-OCT and IVCM are crucial in the diagnosis behind any recurrent corneal erosion. The use of bandage contact lens should be avoided in Meretoja's syndrome to prevent a possible infectious keratitis.

Phototherapeutic keratectomy

Phototherapeutic keratectomy is an excimer laser-based surgical procedure widely performed by corneal surgeons for treating anterior corneal stromal pathologies. Phototherapeutic keratectomy helps by ablating the corneal stroma, thereby improving corneal clarity and smoothening the surface. Transient discomfort and induced hyperopia from corneal flattening are the immediate postoperative concerns. The long-term course is often marked by the recurrence of original corneal pathology and corneal haze formation. Phototherapeutic keratectomy, however, allows for repeat stromal ablation for managing recurrences, as the corneal thickness permits, without affecting the outcome of future keratoplasty. Adjunctive methods such as topical mitomycin-C may be additionally used to reduce recurrence rates. Also, various masking agents such as carboxymethyl cellulose, sodium hyaluronate, and dextran are used in eyes with irregular corneal surface to allow for uniform stromal ablation. Overall, phototherapeutic keratectomy has provided corneal surgeons an additional surgical tool, particularly those residing in developing nations where the availability of donor corneal tissue is an important limiting factor.

Outcomes of keratoplasty in lattice corneal dystrophy in a large cohort of Indian eyes

Purpose:

The purpose of this study is to evaluate the outcomes of keratoplasty for lattice corneal dystrophy (LCD) performed at a tertiary eye care center.

Methods:

A retrospective review of medical records of those patients who were clinically diagnosed to have LCD (72 eyes of 57 patients) and underwent either penetrating keratoplasty (PK, 58 eyes of 46 patients) or deep anterior lamellar keratoplasty (DALK, 14 eyes of 13 patients) between the years 1987 and 2014 was performed. The main outcome measures included demographics, clinical features, and outcomes of keratoplasty.

Results:

The median follow-up after keratoplasty was 3.1 years (interquartile range [IQR], 9 months to 9 years). The median best-corrected visual acuity (BCVA) was 0.18 (IQR, 0.10–0.48) (Snellen equivalent 20/30 [IQR, 20/25–20/60]) at 4 years postoperatively and 0.65 (IQR, 0.18-0.95) (Snellen equivalent 20/89 [IQR, 20/30–20/178]) at 10 years following surgery. DALK eyes had a significantly better BCVA than PK eyes at 2 years following keratoplasty. The median overall survival of grafts was 15.8 years. Late complications included recurrence of LCD (14 eyes), graft infiltrate (23 eyes), graft rejection (15 eyes), graft failure (16 eyes), and glaucoma (14 eyes).

Conclusion:

The outcomes of graft are similar following PK and deep anterior lamellar keratoplasty; however, the latter appears to provide slightly better visual outcome. Recurrence of dystrophy in the graft and graft infiltrates limit the overall graft survival in both the groups.

Vortex Pattern of Corneal Deposits in Granular Corneal Dystrophy Associated With the p.(Arg555Trp) Mutation in TGFBI

PURPOSE

To describe 2 unrelated families with multiple members demonstrating a less commonly recognized vortex pattern of corneal deposits confirmed to be granular corneal dystrophy type 1 (GCD1) after identification of the p.(Arg555Trp) mutation in the transforming growth factor β-induced gene (TGFBI).

METHODS

A slit-lamp examination was performed on individuals from 2 families, one of Mexican descent and a second of Italian descent. After DNA extraction from affected individuals and their unaffected relatives, TGFBI screening was performed.

RESULTS

Eight of 20 individuals in the Mexican family and 20 of 55 in the Italian family demonstrated corneal stromal opacities. Seven of the 8 affected individuals in the Mexican family and 4 of the 20 affected individuals in the Italian family demonstrated a phenotype characterized by a "sea fan" or vortex pattern of superficial stromal corneal deposits originating from the inferior aspect of the cornea. Screening of TGFBI in both families revealed a heterozygous missense mutation [p.(Arg555Trp)] in exon 12, confirming the diagnosis of GCD1.

CONCLUSIONS

Our findings demonstrate that GCD1 may present with a vortex pattern of anterior stromal deposits. Although this pattern of dystrophic deposits is not recognized by clinicians as a typical phenotype of GCD1, it is consistent with the production of the majority of the TGFBI protein by the corneal epithelium.

TGFB1-induced extracellular expression of TGFBIp and inhibition of TGFBIp expression by RNA interference in a human corneal epithelial cell line

PURPOSE

To report the increased production of extracellular transforming growth factor β-induced protein (TGFBIp) by human corneal epithelial cells (HCECs) after induction by TGFB1 and the inhibition of TGFBIp production in induced and noninduced HCECs by RNA interference (RNAi).

METHODS

HCECs were cultured in serum-free medium and treated with 0 or 10 ng/mL TGFB1 over a period of 72 hours. Commercially available siRNAs targeting TGFBI mRNA were mixed with a transfection reagent and used to reverse transfect TGFB1-induced and noninduced HCECs. Extracellular and intracellular concentrations of TGFBIp were measured by ELISA and Western blot analysis, respectively, and TGFBI RNA was assayed using semiquantitative RT-PCR.

RESULTS

HCECs constitutively express TGFBIp, and treatment with TGFB1 results in up to a fourfold increase in the amount of extracellular TGFBIp. Four commercially available siRNAs targeting TGFBI mRNA produced a >70% decrease in extracellular TGFBIp within 48 hours after transfection of noninduced HCECs but a <25% decrease in extracellular TGFBIp by 48 hours after transfection of TGFB1-induced HCECs. The suppression of extracellular TGFBIp production correlated with a decrease in intracellular TGFBIp production and TGFBI mRNA expression after transfection.

CONCLUSIONS

Extracellular TGFBIp expression by HCECs is increased several fold after exposure to TGFB1. Both HCEC-constitutive and HCEC-induced TGFBIp production can be inhibited with RNA interference, though the effect was greater and lasted longer for constitutive than induced TGFBIp production. Given that the corneal deposits in the TGFBI dystrophies consist of TGFBIp derived from HCECs, RNAi represents a potential means to inhibit primary dystrophic deposit formation and recurrence after surgical intervention.

A longitudinal case series investigating cellular changes to the transplanted cornea using confocal microscopy

PURPOSE

To perform a longitudinal evaluation of subjects who had undergone penetrating keratoplasty, using slit scanning confocal microscopy.

METHODS

In vivo confocal microscopy was used to evaluate the central cornea of four subjects who had recently undergone penetrating keratoplasty. Subjects were examined on four occasions over a 12-month period after surgery. Quantitative and qualitative aspects of corneal morphology were compared against data from normal control subjects.

RESULTS

The epithelium varied in appearance between subjects and took at least 12 months to return to a similar arrangement to that seen in normal eyes. Bowman's layer was viewed as an acellular layer immediately after surgery with no evidence of nerve fibres, although nerve components were apparent 12 months after surgery. Stromal nerves were not visible immediately after surgery. One year following penetrating keratoplasty there was evidence of thin nerves running a straight course through the central stroma. Keratocyte density in the anterior and posterior stroma was lower in the transplanted cornea but appeared to remain constant over a period of 1 year. Activated keratocytes were seen in the anterior stroma of all subjects; they appeared to be responsible for significant levels of corneal haze. The time period within which this keratocyte activation occurred varied between individuals. Endothelial cell density decreased at an accelerated rate over the 12-month period.

CONCLUSIONS

Confocal microscopy allows cellular changes to be monitored in vivo following penetrating keratoplasty and may assist clinicians in understanding postoperative recovery.

Excimer Laser Phototherapeutic Keratectomy for Granular and Lattice Corneal Dystrophy: A Comparative Study

PURPOSE

To compare the visual and refractive outcome after excimer laser phototherapeutic keratectomy (PTK) for superficial comeal opacities in granular and lattice dystrophy.

METHODS

Phototherapeutic keratectomy was performed in 62 eyes of 40 patients (granular dystrophy [n = 50] and lattice dystrophy [n = 12]) after epithelial debridement and pannus removal. Data regarding pre-and postoperative best spectacle-corrected visual acuity, changes in spherical equivalent of manifest refraction, Zeiss keratometry, astigmatism, and corneal topography were analyzed and compared between granular and lattice dystrophy. Recurrence, if any, was noted during a mean follow-up of 3.0 +/- 2.7 years.

RESULTS

Best spectacle-corrected visual acuity improved in 79% and 62% of eyes with granular and lattice dystrophy, respectively. Spherical equivalent refraction increased by a mean of 1.3 +/- 1.7 diopters (D) (median: 1.0 D) for granular dystrophy and a mean of 1.0 +/- 1.8 D (median: 0.5 D) for lattice dystrophy. The keratometric central power decreased by a mean of -0.8 +/- 4.3 D (median: -1.6 D) for granular dystrophy and a mean of -0.3 +/- 1.6 D (median: -0.7 D) for lattice dystrophy. No significant changes were noted regarding keratometric astigmatism in either granular or lattice dystrophy. The proportion of "regular" and "mild irregular" keratometry mires increased (39% vs 67% for granular dystrophy and 0% vs 50% for lattice dystrophy). In granular dystrophy, the surface regularity index/surface asymmetry index (SRI/SAI) decreased significantly from 2.14/2.24 preoperatively to 1.31/0.80 postoperatively (P = .006/P = .01). In contrast, decrease of SRI/SAI from 1.97/1.65 preoperatively to 1.35/1.16 postoperatively did not reach statistical significance in lattice dystrophy. Recurrences were observed in 10 (20%) eyes with granular dystrophy and 2 (17%) eyes with lattice dystrophy.

CONCLUSIONS

Our results suggest that PTK may be tried in all patients with superficially accentuated opacities in granular and lattice dystrophy before undergoing a more invasive procedure, such as lamellar or penetrating keratoplasty.

Morphometric analysis of deposits in granular and lattice corneal dystrophy: histopathologic implications for phototherapeutic keratectomy

OBJECTIVE

To quantify the distribution and size of deposits in granular and lattice corneal dystrophies and to estimate the impact of these findings on the potential benefit of phototherapeutic keratectomy (PTK) as primary treatment in these corneal disorders.

METHODS

Central histologic sections of consecutive corneal buttons (34 granular dystrophy specimens of 27 patients (mean age 53 +/- 12 years) and 20 lattice dystrophy specimens of 20 patients (mean age 50 +/- 17 years) obtained from central penetrating keratoplasty were examined by light microscopy using Masson trichrome and Congo Red stains. Localization and anterioposterior diameter of the most superficial, the deepest, and the largest deposits were quantified in the central and the two peripheral thirds of the specimens. Bowman layer status and thickness of the epithelium were recorded. The clear central corneal zone size before and after a hypothetical superficial PTK (100-microm ablation) was calculated.

RESULTS

Central deposits in granular dystrophy were mostly superficial (mean distance from the epithelium 28 +/- 19 microm) and associated with Bowman layer and epithelial changes. In lattice dystrophy, deposits were mostly midstromal (mean distance from the epithelium 79 +/- 54 microm, P < 0.001) with a larger scatter, showing minor superficial involvement. After a fictitious PTK, a significant increase in mean clear central zone was achieved (P = 0.004). This increase in mean clear central zone was more pronounced in granular (from 484 +/- 389 microm to 1451 +/- 1954 microm) than in lattice (from 258 +/- 183 microm to 846 +/- 784 microm) dystrophy (P = 0.004). Deposits were completely removed in 22% of the granular dystrophy samples. In both dystrophies, a clear central "pinhole" greater than 1 mm in diameter was achieved in around one third of corneas.

CONCLUSION

According to the histopathologic corneal deposit size and distribution, PTK may be an effective treatment to increase visual acuity in patients with granular dystrophy more than in those with lattice dystrophy, to delay or even avoid penetrating keratoplasty.

Recurrence of corneal stromal dystrophies after penetrating keratoplasty

PURPOSE

To assess the rates of simple and clinically significant recurrences of stromal dystrophies in corneal grafts.

METHODS

We conducted a retrospective review of Wills Eye Hospital records from 1984 to 2001, identifying all patients with stromal corneal dystrophies who had penetrating keratoplasties. Kaplan-Meier curves and chi analysis were performed.

RESULTS

The study population consisted of 35 eyes (21 patients) with lattice dystrophy, 17 eyes (10 patients) with corneal dystrophy of Bowman's membrane (CDB), 14 eyes (eight patients) with macular dystrophy, seven eyes (five patients) with granular dystrophy, and four eyes (four patients) diagnosed with Schnyder's crystalline dystrophy. There was a simple recurrence in 21 (60%) eyes (14 patients) with lattice and in 15 (88%) eyes (eight patients) with CDB. The median time to simple recurrence for the first eye transplanted of each patient was 8.4 years for lattice and 2.0 years for CDB. After 5 years of follow-up, there was a clinically significant recurrence, manifested by recurrent erosions or associated with decreased visual acuity, in the first eye transplanted of each patient, respectively, in six (17.1%) and seven (20%) eyes with lattice and in two (11.8%) and three (17.6%) eyes with CDB.

CONCLUSION

Corneal dystrophy of Bowman's membrane has the highest rate of simple recurrence followed by granular and lattice dystrophies, respectively. However, the rate of clinically significant recurrence, both recurrent erosions and decreased visual acuity, in the first 5 years is similar in CDB and lattice dystrophies. Recurrence is infrequent in macular and Schnyder's crystalline dystrophy. As expected, in genetic diseases, the potential for recurrence exists and increases with follow-up time.

Differences in amyloid deposition in primary and recurrent corneal lattice dystrophy type 1

PURPOSE

To report the histopathology of a case of recurrent corneal lattice dystrophy showing altered distribution of the corneal deposits in the recurrent disease compared with the original.

METHODS

Clinical details and histopathology of the primary and repeat corneal grafts are reported.

RESULTS

A woman originally presented at age 28 years with reduced visual acuity and classic corneal lattice lines in both corneas and underwent bilateral corneal grafts. Recurrent disease was detected 20 years later as anterior haze and various-sized subepithelial opacities but no stromal lattice lines. Histology of the original corneas demonstrated amyloid deposits throughout the corneal stroma, typical of corneal lattice dystrophy. In the repeat grafts, amyloid deposits were confined to the basement membrane region of the anterior cornea and were almost entirely absent from the stroma of the cornea.

CONCLUSION

Recurrence of corneal lattice dystrophy is widely recognized to occur, but the pathology of the recurrent disease is not well documented in the literature. This case report highlights that there may be a difference in the distribution of the deposits when the disease recurs. We postulate that the reason for this difference may be that donor keratocytes survive long enough in the transplanted cornea to prevent build-up of abnormal keratoepithelin, the product of the mutated gene in type 1 corneal lattice dystrophy. By contrast, the epithelium, being replaced by host epithelium shortly after grafting, is still producing abnormal protein. The differences in the pattern of deposits may have important clinical implications, particularly regarding treatment modalities in recurrent disease.

A new clinical perspective of corneal dystrophies through molecular genetics

In the past 2 years, significant advances have been made in the genetics of corneal dystrophies. Genetic heterogeneity (one disease condition caused by single mutations in any one of multiple genes) and phenotypic diversity (many disease conditions caused by mutations in a single gene) are common emerging themes. Genetic heterogeneity in Meesmann corneal dystrophy was established with the identification of two causative genes, keratins 3 and 12, that encode cytoskeletal proteins. Conversely, mutations in a single gene, keratoepithelin, were found to cause several distinct corneal dystrophies affecting the Bowman layer and the stroma. We present a novel preliminary classification of corneal dystrophies based on molecular etiology. This classification may be useful in understanding the pathogenesis of corneal dystrophies and in developing new strategies to treat these dystrophies.

Transforming growth factor-beta induced protein, betaIG-H3, is present in degraded form and altered localization in lattice corneal dystrophy type I

Lattice corneal dystrophy type I (LCDI) is an inherited autosomal dominant local amyloidosis, restricted to the corneal stroma. Comparison of electrophoretic profiles of normal and dystrophic corneas revealed a 42 kD protein, which was present only in dystrophic corneas. The N-terminal sequence of this protein showed identity to transforming growth factor-beta induced gene product (betaIG-H3). A polyclonal antiserum was raised in chicken against a synthetic peptide identical to the N-terminal portion of betaIG-H3. On immunoblots, the antiserum stained the 42 kD band, and also a 68 kD band corresponding to the reported molecular weight of the intact betaIG-H3. In normal corneas, only the 68 kD band was present. Immunohistologically, the antiserum stained corneal subepithelial regions, including subepithelial deposits, in dystrophic corneas. In normal corneas, the staining was observed only in the epithelium. These results may reflect the role of betaIG-H3 in extracellular matrix construction and/or amyloid formation.

Clinical follow-up of 193-nm ArF excimer laser photokeratectomy

The excimer laser has been undergoing rapid development for clinical use since the early 1980s. The authors report 2-year follow-up results from studies in 31 eyes (15 women and 14 men) to evaluate the excimer laser in performing photokeratectomy. Patients were divided into two groups: 27 eyes (group 1) underwent phototherapeutic keratectomy, and 4 eyes (group 2) underwent photorefractive keratectomy. Visual function improved in 21 of 27 eyes in group 1 and in 2 of 4 eyes in group 2. Complications were minimal and manageable. The authors describe a procedure to minimize induced hyperopia in phototherapeutic keratectomy patients, and, although not statistically significant, less induced hyperopia was noted in these patients. Photokeratectomy may be an alternative to penetrating or lamellar keratoplasty and more invasive refractive procedures, but the long-term effects must be carefully observed.

Recurrence of posterior polymorphous corneal dystrophy after penetrating keratoplasty

Recurrence of a corneal dystrophy after keratoplasty can occur in multiple dystrophies, including macular, granular, and lattice dystrophies. We treated two unrelated patients who had documented posterior polymorphous dystrophy and who, in previously clear grafts, developed haziness in the zone of Descemet's membrane, which led to graft failure. Histologic examination of the keratoplasty specimen showed changes typical of posterior polymorphous dystrophy.