Limbal graft transplantation: a rare implementation in pediatric limbal stem cell deficiency.

PURPOSE: To evaluate limbal graft transplantation success in pediatric patients with chemical injury-induced limbal stem cell deficiency (LSCD) using the 'LSCD Working Group' staging system. METHODS: Medical records of 11 eyes of 11 children who underwent limbal graft transplantation (limbal autograft/limbal allograft) were included. Surgical success was defined as improvement in the post-operative 1st year LSCD stage. RESULTS: The mean age was 12 ± 5 (4-17) years. Causative agent was alkaline in 4(36.4%) and acid in 3(27.2%) patients. Limbal autograft was performed in 9 (81.8%) eyes with unilateral LSCD, and allograft transplantation was performed in 2 (18.2%) eyes with bilateral LSCD. The mean follow-up time was 33.89 ± 30.73 (12-102.33) months. The overall limbal graft transplantation success rate was 72.7%. Among 9 patients who receive limbal autograft, 8 had improvement in post-operative LSCD stage, 1 had stable LSCD stage. Of the 2 patients who receive limbal allograft, post-operative LSCD stage remained the same in 1 and worsened in 1 patient. The mean time between injury and the surgery was 30.47 ± 30.08 (7-108.47) months. Penetrating keratoplasty was performed in 3 (27.2%) of 11 patients following limbal graft transplantation. CONCLUSION: Management of LSCD in children is challenging and appears to be somewhat different from that of adults. Limited data in the literature indicate that cultivated or simple limbal epithelial transplantations (CLET/SLET) are primarily preferred in children. Although the tendency to take small tissue from the healthy eye is noteworthy, conventional limbal allograft and autograft transplantations also show promising results without any further complications in at least 1 year follow-up period.

Demographic Data and Trends in Use of Amniotic Membrane Transplant During the Past Decade at a Tertiary Eye Center.

OBJECTIVES: In this study, we aimed to define demographic data and trends in use of amniotic membrane transplant during the past decade at a tertiary eye center. MATERIALS AND METHODS: We included 272 patients who underwent amniotic membrane transplant for ocular surface pathology from January 2009 to December 2021. We retrospectively evaluated the medical data. RESULTS: The male-to-female ratio of patients was 41/23. Mean age of the patients was 50 ± 23.6 years (range, 1-91 years). Indications consisted of ocular surface lesion excision surgery (n = 184; 66.7%), chemical injury (n = 25; 9.1%), persistent epithelial defect (n = 23; 8.3%), keratitis (n = 22; 8%), noninfectious corneal perforation (n = 9; 3.3%), bullous keratopathy (n = 9; 3.3%), and ocular cicatricial pemphigoid (n = 4; 1.4%). Single amniotic membrane transplant was applied to 236 patients (85.5%), and multiple transplant was applied to 40 patients (14.5%). We observed repeated amniotic membrane transplant rates and amniotic membrane degradation durations that were associated with primary disease (P = .005 and P < .001, respectively). Degradation time was shorter in cases of chemical burns and keratitis than in cases after ocular surface lesion excision. Amniotic membrane transplant indication rates were statistically different between the first 6 years and the last 6 years of the 12 years of data (P = .041). The frequency of amniotic membrane transplant application in microbial keratitis has increased substantially in the past 2 years. CONCLUSIONS: Amniotic membrane is used as a biomaterial in various ocular surface diseases due to its anti-inflammatory, antimicrobial, and wound-healing properties. After transplant, the amniotic membrane, which is directly related to the inflam-matory processes of the primary disease, degrades gradually. There may be changes in the trend of amniotic membrane transplant, the indications of which are progressively expanding over time.

Evaluation of scleral thickness in patients with pterygium.

OBJECTIVES: To evaluate scleral thickness measurements of pterygium patients using anterior segment optical coherence tomography (AS-OCT) and to compare them with healthy individuals. MATERIAL AND METHODS: Scleral thickness was measured from 2, 4, 6 mm posterior to the scleral spur with AS-OCT (Swept Source OCT Triton, Topcon, Japan) in 4 quadrants (superior, inferior, nasal and temporal). RESULTS: Eyes with pterygium were determined as Group 1, and contralateral eyes without pterygium were determined as Group 2. Healthy controls were determined as Group 3. In the measurements made from 4 mm posterior, no significant difference was found between Group 1 and Group 2 in any quadrants (p > 0.05). In all measurements made from 4 mm posterior to the scleral spur, scleral thickness was found to be significantly higher in Group 1 compared to Group 3 (p < 0.05). Measurements made from 2 mm posterior to the scleral spur in Group 1 was found to be significantly higher in the superior and temporal quadrants compared to Group 3 (p = 0.05), while no significant difference was found in the nasal and inferior quadrants (p > 0.05). When Group 2 and Group 3 were compared, scleral thickness measurements made from 4 mm posterior to the scleral spur was significantly thicker in all quadrants in Group 2 (p > 0.05). CONCLUSION: Scleral thickness was found to be higher in pterygium patients compared to healthy controls, especially when measured from 4 mm posterior to the scleral spur. It has been predicted that high scleral thickness may be associated with high fibroblast activity in subconjunctival structures, and this may predispose to pterygium.

Severity Classification of Limbal Stem Cell Failure Due to Steven Johnson Syndrome in the Light of the Classification Consensus of Limbal Stem Cell Deficiency.

OBJECTIVES: To examine and to understand the limbal stem-cell deficiency (LSCD) because of Steven-Johnson syndrome (SJS) in line with the new classification system for the first time in the literature. METHODS: Medical records of patients with LSCD because of SJS were reviewed retrospectively. In addition to demographic data and ophthalmologic or systemic findings, anterior segment photographs of the patients were reviewed retrospectively. Limbal stem-cell deficiency severity was graded according to the classification published by the Limbal Stem Cell Working Group. RESULTS: Twenty-four eyes of 14 patients with eye involvement secondary to SJS were included in the study. The mean age of the patients was 36.09±16.70 (9-58) years and the female-to-male ratio was 11:3. The anterior segment photographs of the patients were evaluated by two independent masked observers. Limbal stem-cell deficiency severity was graded according to the classification published by Deng et al. Corneal opacity was divided into three stages according to the area of involvement. Corneal opacity was classified as Stage I if the central 5 mm region of the cornea was not affected, as Stage II if the central 5 mm region of the cornea was affected, and as Stage III if the entire corneal surface was affected. Limbal involvement was classified as Stage A if it was below 50%, as Stage B if it was between 50% and 100%, and as Stage C if it was 100%. CONCLUSION: This is the first study in the literature to describe and classify LSCD because of SJS, according to the new LSCD classification. Consistent with the results, LSCD follows a bimodal distribution. Most patients demonstrated severe (Stage III-32.14%) or mild (Stage IA-21.42%) LSCD.

Ocular manifestations of granulomatosis with polyangiitis: report from a tertiary eye care center.

PURPOSE: To report demographic characteristics and ophthalmological manifestations of patients with granulomatosis with polyangiitis (GPA) in a tertiary eye care center in Turkey. METHODS: Medical records of patients with GPA-related ocular manifestations evaluated between 2013 and 2023 were included. Demographic and clinical characteristics of the patients including nature of systemic involvement, ophthalmologic symptoms and signs, laboratory investigations and treatment modality were reviewed. RESULTS: Twelve eyes of 10 patients (5 female/5 male) were included. The mean age was 57.2 ± 12.2 (35-71) years. Five (50%) patients were already diagnosed with GPA. Ocular involvement was the first manifestation of GPA in 3 patients. The remaining 2 patients had simultaneous systemic and ocular symptoms at presentation. Conjunctival hyperemia (9 eyes) and pain (7 eyes) were the most frequent presenting symptoms followed by blurred vision (3 eyes). The frequencies of ocular manifestations were as follows:episcleritis (3 eyes), isolated peripheral ulcerative keratitis (PUK) (3 eyes), scleritis (3 eyes), simultaneous PUK and scleritis (2 eyes) and periorbital mass (1 eye). CONCLUSION: Ophthalmological manifestations can be the initial findings in GPA. Since GPA can affect different structures of the eye, it sometimes might be challenging for ophthalmologists. Therefore, it is crucial for ophthalmologists to be well-informed about GPA-related ocular findings and to have a high index of suspicion for GPA. Although PUK associated with scleritis is highly suggestive for GPA, isolated cases of PUK or scleritis can be seen in GPA. Therefore, it is important to adopt a multidisciplinary approach, consider GPA in differential diagnosis, and benefit from accurate diagnostic tests.

An important detail that is still not clear in amniotic membrane applications: How do we store the amniotic membrane best?

The use of fresh amniotic membrane (AM) is not a viable option, as it has many disadvantages. Preserving the AM reduces the risk of cross-infection and maintains its effectiveness for a long time. In order to maximize the therapeutic effects of the AM, the basic need is to preserve its vitality and the bioactive molecules it contains. However, the effect of preservation procedures on cell viability and growth factors is a still matter of debate. Optimum preservation method is expected to be cost-effective, easily-accessible, and most importantly, to preserve the effectiveness of the tissue for the longest time. However, each preservation technique has its advantages and disadvantages over the other, and each one compromises the vitality and bioactive molecules of the tissue to some extent. Therefore, the best method of preservation is still controversial, and the question of 'how to preserve the AM best?' has not yet been definitively answered.

Impression Cytologic Evaluation of the Conjunctiva in Patients Treated with Topical 1% Voriconazole

Objectives: The aim of the present study was to evaluate any conjunctival metaplastic changes by impression cytology in patients who underwent topical 1% voriconazole treatment for severe fungal keratitis. Materials and Methods: The study was conducted at Ege University Faculty of Medicine, Departments of Ophthalmology and Medical Pathology. Patients who were treated with 1% topical voriconazole for fungal keratitis for at least 3 months were included. The used topical voriconazole treatment was initiated as one drop every hour and was tapered according to clinical improvement in all patients. Treatment was continued 4 times a day for at least 3 months. Impression cytology samples were collected at least 3 months after cessation of topical voriconazole from the affected eyes and from the fellow eyes as a control group. Collected specimens were transferred to the pathology department for evaluation and grading (Nelson's grading system). Results: The mean age of the patients was 57.68±17.32 years (range, 22-87 years). The impression cytology grade of the inferior bulbar conjunctiva was 1.73±0.77 (range, 0-3) in the study group and 1.19±0.98 (range, 0-3) in the control group (p=0.03). The impression cytology grade of the temporal bulbar conjunctiva was 1.69±0.73 (range, 0-3) in the study group and 1.15±0.88 (range, 0-3) in the control group (p=0.02). The impression cytology grades of the nasal and superior bulbar conjunctiva did not differ statistically (p values 0.13 and 0.17, respectively). Conclusion: Topical voriconazole is an effective broad-spectrum antifungal drug, but it induces conjunctival squamous metaplasia. Clinicians should be aware of this possible side effect of topical voriconazole and should carefully evaluate the conjunctiva of treated patients at each visit to detect possible metaplastic changes.

Amniotic Membrane Transplantation for Reconstruction of Ocular Surface Lesion Excisions in Pediatric Population.

PURPOSE: To define the use of human amniotic membrane transplantation (hAMT) for reconstruction of the ocular surface after ocular surface lesion excisions in pediatric population during the last decade in a tertiary eye center. METHODS: A total of 31 patients who underwent hAMT procedure because of the excision of ocular surface lesions between January 2009 and December 2021 were included in this study. The medical data were retrospectively evaluated. RESULTS: The female-to-male ratio was 14/17. The mean age of the patients was 10.1±4.1 (range, 1-18) years. Although a single hAMT was applied to most of the cases (94.4%; 34 eyes), more than one hAMT was applied to 5.6% of cases (2 eyes). The amniotic membrane degradation duration was found to be 21.5±10.8 (range, 13-50) days. CONCLUSIONS: Amniotic membrane is used as a biomaterial in various ocular surface diseases with its anti-inflammatory, antimicrobial, and wound healing properties. Although widely used, there are only a few studies reporting its clinical efficacy in the pediatric age group. It seems to be safe and effective in pediatric age group for ocular surface reconstruction after ocular surface lesion excisions.

Clinical Approach to Ocular Cicatricial Pemphigoid.

Objectives: To evaluate the demographic data, ocular and systemic findings, clinical management, and outcomes of patients with ocular cicatricial pemphigoid (OCP). Materials and Methods: The medical records of 11 patients diagnosed as having OCP in the ophthalmology department of Ege University between 2008 and 2021 were evaluated retrospectively. Results: The patients' mean follow-up time was 14±5.76 months. All eyes (100%) had conjunctival involvement and 18 (81.81%) had corneal involvement. According to the Tauber staging system, 7 (31.81%), 8 (36.36%), and 7 (31.81%) of the eyes were stage 2, 3, and 4, respectively. The diagnosis was confirmed in 6 (66.66%) of 9 patients who underwent biopsy. Amniotic membrane transplantation was performed in 7 eyes, entropion surgery in 2 eyes, and electrocauterization for trichiasis in 5 eyes. Systemic involvement was observed in 45.45% (5/11) of patients, most commonly oral mucosal involvement (18.18%). Review of medical records showed that alkylating agents, steroids, and dapsone were used in patients treated before 2020. Mycophenolate mofetil was preferred to be used in combination with corticosteroids. Although treatment responses before mycophenolate mofetil usage could not be evaluated well because of loss to follow-up, 4 (66.66%) of 6 patients who received steroid treatment combined with mycophenolate mofetil showed partial or complete clinical remission. No serious side effects and drug withdrawal were observed. Conclusion: OCP is a sight-threatening autoimmune disease that affects older adults. Although positive biopsy results are valuable for diagnosis, negative results do not exclude the diagnosis. The main treatment is systemic immunosuppressives. Disease activity can be suppressed, especially with early initiation of drug therapy. These patients require a multidisciplinary approach. Especially in the presence of isolated ocular findings, ophthalmologists should be able to make the decision to start immunosuppressive treatment, and systemic treatment should not be delayed.

Identification of Normal Fornix Depth Dataset Generated with a Validated Fornix Meter in Healthy Turkish Population.

PURPOSE: To provide an age and sex-classified reference dataset for normal fornix depth by measuring the lower and upper conjunctival fornix depth (FD) in healthy volunteers. METHODS: An epidemiological, prospective, cross-sectional study evaluates conjunctival FDs in 301 healthy Turkish volunteers aged 20-83. Fornix measurements were made using a validated fornix depth measurer (FDM). RESULTS: The mean age was 49.2 ± 19 in males and 48.6 ± 16.2 in females. The mean upper and lower conjunctival FDs were 15.9 (12-21) mm and 10.1 (6-13) mm, respectively. The mean upper and lower FDs were 15.4 (13-20) mm and 9.7 (6-13) mm in females, and 16.3 (12-21) mm and 10.5 (8-13) mm in males, respectively. . CONCLUSION: When the normative dataset created in healthy Turkish volunteers, it was observed that both the upper and lower FDs were shallower in females and that they gradually became shallower with age. Accordingly, when an evaluation for conjunctival pathology is to be made, the expected normal FD value for both age and sex should be considered.

An Operational Burden Issue: Deciding on a Corneal Recipient From the Corneal Transplant Wait List for Elective Corneal Transplant.

The cornea is the outermost tissue of the eye and must be transparent to maintain good visual function. Diseases with loss of corneal transparency (ie, corneal blindness) account for 10% of blindness worldwide. The treatment of this condition is only possible with corneal transplant from corneal tissue obtained from deceased donors. More than 10 million people worldwide have corneal blindness, but the annual number of available corneal transplants is only 185 000. Accordingly, it is obvious that the quantity of available donor tissue does not meet the need, with nearly 70 candidates on the wait list for each available corneal transplant. Rapid identification of appropriate recipients has become a crucial element in the field of corneal transplantation. There is a similar urgency (and scarcity) in other solid-organ donation programs, most of which have an established set of selection parameters (such as blood enzyme levels) that are easily defined and measurable. However, in the case of corneal transplant, there is presently no worldwide consensus on such selection criteria. The corneal transplant wait lists are long. The selection of appropriate recipients from these wait list candidates is managed by a designated authority (the authorized recipient selection operator) informed by the literature and the characteristics of the recipient within a framework of generally accepted, but variable, guidelines. The decision process is encumbered to a degree proportionate to the length of the wait list. In this review, we focus on solutions documented in the literature for selection of appropriate corneal recipients from transplant wait lists.

Fungal Keratitis and Corneal Perforation as a Rare Complication of Corneal Collagen Cross-Linking Treatment.

PURPOSE: The aim of this study was to report a case of fungal keratitis with subsequent corneal perforation after corneal collagen cross-linking (CXL) treatment performed for keratoconus. CASE REPORT: A 20-year-old woman presented with redness and discharge in the left eye. She had a history of bilateral CXL procedure performed for keratoconus elsewhere 4 days earlier. The visual acuity was hand motion in the left eye. Slit-lamp examination revealed extended corneal melting with surrounding infiltrates. The patient was hospitalized, and corneal epithelial scraping samples were sent for microbiological assessment. In the meantime, empirical antibiotic therapy (fortified topical antibiotics: vancomycin 50 mg/mL, ceftazidime 50 mg/mL, and fluconazole 2 mg/mL q1 hour) was initiated. In direct microscopy of the corneal scraping, septate hyaline fungal hyphae were detected and topical fluconazole was switched to topical voriconazole (10 mg/mL). Three days after hospitalization, corneal melting progressed to perforation and corneal suturing with 10-0 monofilament was performed to reform the anterior chamber. Complete resolution of keratitis with residual scarring was noticed in 2 weeks. Three months later, penetrating keratoplasty was performed to obtain better visual acuity. CONCLUSIONS: CXL with riboflavin has become a common procedure to prevent keratoconus progression by strengthening the biomechanical specialties of the cornea. Although the treatment itself has been used in the management of microbial keratitis and related corneal melting, fungal keratitis and corneal perforation after a CXL procedure for keratoconus might also be detected. Clinicians should be aware of this rare but devastating complication of CXL treatment and start prompt treatment when suspected.

Evaluation of the factors that influence surgical outcome in conjunctival-limbal allograft transplantation.

OBJECTIVE: To evaluate the surgical results and the variables affecting the outcomes in conjunctival-limbal allograft transplantation (CLAL). METHODS: Patients who underwent CLAL for limbal stem cell deficiency (LSCD) between 2007 and 2019 were included in the study. LSCD staging was performed according to the staging system developed by the 'Limbal Stem Cell Working Group'. Stage 1C and higher stage LSCD patients were included in the study. 'Successful surgical outcome' was defined as improvement in LSCD stage at 1 year postoperatively. RESULTS: A total of 19 eyes of 19 LSCD patients were included. The mean age of the patients was 40.21 ± 14.65 (6-65) years, and the male/female ratio was 12/7. CLAL was performed in 9 (47.3%) patients with Stage 2B, 9 (47.3%) patients with Stage 3 and 1 (5.4%) with Stage 1C. LSCD aetiology; chemical injury (12), vernal keratoconjunctivitis (2), aniridia (1), corneal degeneration (1), and unknown (3). Surgery was successful in 52.6% of cases. Surgical success was associated with lower LSCD stage (p = 0.04). Lower grades of chemical injury at presentation and a longer time interval between injury and CLAL were associated with higher surgical success (p = 0.001; p = 0.001). The mean postoperative follow-up time was 50.77 ± 29.46 (6-98) months. CONCLUSIONS: Despite graft rejection and long-term use of immunosuppressants, CLAL is still one of the most preferred techniques in the treatment of bilateral LSCD. Preoperative LSCD stage and degree of chemical burn are important factors affecting the surgical outcome. Also, CLAL surgery should not be rushed and should be performed when inflammation has subsided.

Precision of limbal ischemia evaluation in ocular chemical injuries with anterior segment optical coherence tomography angiography.

PURPOSE: To evaluate the limbal ischemia objectively in ocular surface chemical injuries by using anterior segment optical coherence tomography angiography (AS-OCTA). METHODS: In this cross-sectional study, acute ocular surface chemical injury patients with less than 1 week injury history were enrolled. Demographic data of the patients were noted, and detailed ophthalmological examination with Dua classification was performed. AS photographs and AS-OCTA images were obtained and used for the assessment of limbal ischemia. To visualize the limbal vasculature, the device was focused manually to get a sharp image for all 4 quadrants of the limbus. The absence of vasculature was regarded as "ischemia," and the amount of the ischemia was defined in clock hours. The limbal ischemia detected in clinical evaluation with biomicroscopy was compared with the AS-OCTA detected ischemia amount to make a conclusion for the correlation. RESULTS: Nineteen eyes of 18 patients with acute ocular surface chemical injury were enrolled to the study (2 female, 16 male). The mean age was 35.1 ± 10 (18-55), and the mean best corrected visual acuity was 0.75 ± 1 (0.1-3.1) LogMAR. The causative agents were acid in 6 and alkaline in 12 patients. Limbal ischemia detected by using AS-OCTA was greater ((5.8 ± 2.6 (2-10) clock hours) than that detected in biomicroscopy (4.8 ± 2.4 (2-12) clock hours). The difference was statistically significant (p < 0.0005). CONCLUSION: AS-OCTA has a significant importance on limbal vascularity visualization; therefore, its use for more objective and sensitive evaluation of limbal ischemia in ocular surface chemical injuries seems to have a crucial impact. AS-OCTA images may reveal the extension of limbal ischemia more precisely than clinical evaluation with biomicroscopy. However, future studies with higher number of patients are needed to come to a specific conclusion.

Evaluation of Limbal Stem Cell Transplant Success in Ocular Chemical Injury.

OBJECTIVES: We evaluated limbal stem cell transplant success in limbal stem cell deficiency due to chemical injury at a tertiary eye care center in Turkey with a novel system for describing limbal stem cell deficiency, as developed by the Limbal Stem Cell Working Group. MATERIALS AND METHODS: Medical records of 80 eyes of 80 patients after limbal stem cell transplant for limbal stem cell deficiency secondary to chemical injury were included, with patients grouped according to surgical procedure, ie, limbal autograft, limbal allograft, and cultivated limbal epithelial cell transplant. Surgical success was defined as improvement in postoperative year 1 of limbal stem cell deficiency stage. RESULTS: Patients' mean age was 37.9 ± 15.7 years (range, 4-71 years). Male/female ratio was 2.4. Forty-five patients (56.3%) were injured with alkaline substance, and 16 (20%) with acid substance. Mean follow-up time was 60.3 ± 30.6 months (range, 6-118.6 months). Limbal autograft, allograft, and cultivated limbal epithelial cell transplants were performed in 58 (72.5%), 12 (15%), and 10 (12.5%) eyes, respectively. Intervals between injury and surgery in limbal autograft, limbal allograft, and cultivated limbal epithelial cell transplants were 43.3 ± 94.1 months (range, 0.5-592 months), 14.5 ± 10.6 months (range, 2.4-32.5 months), and 122.8 ± 158.9 months (range, 21.1-504 months),respectively (P = .02); and surgical success rates in each group were 65.5%, 41.7%, and 90%, respectively (P = .03). Overall surgical success rate was 65%. CONCLUSIONS: Accurate determination of the limbal stem cell deficiency stage is crucial for proper evaluation of surgical success. Surgery type and interval between injury and surgery were the most important factors associated with higher surgical success rates. Despite the limited number of patients in the subgroups, the results were remarkable to emphasize the significance of a novel limbal stem cell deficiency scoring system.

Correction of high astigmatism with toric intraocular lens in eyes with corneal transplant.

OBJECTIVES: To evaluate the results of toric intraocular lens (IOL) implantation during cataract surgery in eyes with high regular astigmatism associated with prior penetrating keratoplasty (PK). METHODS: A retrospective data analysis of patients with prior PK, who underwent uncomplicated cataract surgery with hydrophobic toric single piece IOL (EyeCryl Toric®, Biotech Vision Care, Luzern, Switzerland). RESULTS: A total of 18 eyes of 18 patients were included in the study. The mean age was 53.4 ± 12.4 (25-70) years. The mean follow-up period was 15.5 (4-24) months. The mean best corrected visual acuity (BCVA) significantly increased from 1.36 ± 1.0 logMAR to 0.31 ± 0.17 logMAR (p < .001) pre- and post-operative 4 weeks, respectively. There was no significant change in mean BCVA during follow-up; mean BCVA was 0.32 ± 0.17 logMAR at the last visit. The mean pre-operative topographic astigmatism was 6.52 ± 1.80 diopters (D). The mean manifest refraction astigmatism was decreased from 6.55 ± 1.62 D to 2.80 ± 1.43 D (p˂0.001). The mean Surgically induced astigmatism (SIA) was 3.74 ± 0.77 D according to vector analysis. There was no patient with graft rejection or failure, the mean endothelial cell loss rate was 12.75 ± 3.76% (7-17%). There was no patient requiring IOL reposition. CONCLUSIONS: Toric IOL implantation during cataract surgery provides an option to correct astigmatism in post-PK eyes with high regular astigmatism. When appropriate patients are selected it is a safe method to achieve significant improvements in visual acuity and astigmatism.