Rose K. Sia

Chronic dry eye in photorefractive keratectomy and laser in situ keratomileusis: Manifestations, incidence, and predictive factors

Purpose To evaluate dry‐eye manifestations after photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) and determine the incidence and predictive factors of chronic dry eye using a set of dry‐eye criteria. Setting Walter Reed Army Medical Center, Washington, DC, USA. Design Prospective, non‐randomized clinical study. Methods Dry‐eye evaluation was performed before and after surgery. Main outcome measures included dry‐eye manifestations, incidence, and predictive factors of chronic dry eye. Results This study comprised 143 active‐duty U.S. Army personnel, ages 29.9 ± 5.2 years, with myopia or myopic astigmatism (manifest spherical equivalent −3.83 ± 1.96 diopters) having PRK or LASIK. Schirmer scores, corneal sensitivity, ocular surface staining, surface regularity index, and responses to dry‐eye questionnaire significantly changed over time after PRK. After LASIK, significant changes were observed in tear breakup time, corneal sensitivity, ocular surface staining, and responses to questionnaire. Twelve months postoperatively, 5.0% of PRK and 0.8% of LASIK participants developed chronic dry eye. Regression analysis showed that pre‐operatively lower Schirmer score will significantly influence development of chronic dry eye after PRK, whereas preoperatively, lower Schirmer score or higher ocular surface staining score will significantly influence the occurrence of chronic dry eye after LASIK. Conclusions Chronic dry eye was uncommon after PRK and LASIK. Ocular surface and tear‐film characteristics during pre‐operative examination might help to predict chronic dry‐eye development in PRK and LASIK. Financial Disclosure The authors have no financial interest in any product, drug, instrument, or equipment discussed in this manuscript.

Polymorphism in THBS1 Gene Is Associated with Post-Refractive Surgery Chronic Ocular Surface Inflammation

PURPOSE To determine the association of single nucleotide polymorphisms (SNPs) of the thrombospondin 1 (THBS1) gene with development of chronic ocular surface inflammation (keratoconjunctivitis) after refractive surgery. DESIGN Retrospective cohort study. PARTICIPANTS Active duty U.S. Army soldiers (n = 143) who opted for refractive surgery. METHODS Conjunctival impression cytology samples collected from participants before the surgery were used to harvest DNA for genotyping 5 THBS1 SNPs (rs1478604, rs2228262, rs2292305, rs2228262, and rs3743125) using the Sequenom iPLEX Gold platform (Sequenom, San Diego, CA). Samples collected after surgery were used to harvest RNA for gene expression analysis by real-time polymerase chain reaction (PCR). Participants were followed for 1 year after surgery to monitor the status of keratoconjunctivitis. MAIN OUTCOME MEASURES Genetic basis of the development of chronic keratoconjunctivitis after refractive surgery. RESULTS Carriers of minor alleles of 3 SNPs each were found to be more susceptible to developing chronic keratoconjunctivitis (rs1478604: odds ratio [OR], 2.5; 95% confidence interval [CI], 1.41-4.47; P = 2.5 × 10(-3); rs2228262 and rs2292305: OR, 1.9; 95% CI, 1.05-3.51; P = 4.8 × 10(-2)). Carriers of the rs1478604 minor allele expressed significantly reduced levels of thrombospondin 1 (TSP1) (P = 0.042) and increased levels of an inflammatory cytokine associated with keratoconjunctivitis, interleukin-1β (P = 0.025), in their ocular surface epithelial cells compared with homozygous major allele controls. CONCLUSIONS Genetic variation in the THBS1 gene that results in decreased expression of the encoded glycoprotein TSP1 in ocular surface epithelial cells significantly increases the susceptibility to develop chronic ocular surface inflammation after refractive surgery. Further investigation of THBS1 SNPs in a larger sample size is warranted.

A Cleavage-potentiated Fragment of Tear Lacritin Is Bactericidal

Background: The wet visual surface of the eye is essentially a sterile environment. Results: Proteolytic processing of the prosecretory mitogen lacritin in tears releases a fragment that is required for much of the bactericidal activity of tears. Conclusion: The protease-released C terminus of lacritin is bactericidal under physiological conditions. Significance: All known lacritin activities are bundled within the same C-terminal region, although at different dose optimum. Antimicrobial peptides are important as the first line of innate defense, through their tendency to disrupt bacterial membranes or intracellular pathways and potentially as the next generation of antibiotics. How they protect wet epithelia is not entirely clear, with most individually inactive under physiological conditions and many preferentially targeting Gram-positive bacteria. Tears covering the surface of the eye are bactericidal for Gram-positive and -negative bacteria. Here we narrow much of the bactericidal activity to a latent C-terminal fragment in the prosecretory mitogen lacritin and report that the mechanism combines membrane permeabilization with rapid metabolic changes, including reduced levels of dephosphocoenzyme A, spermidine, putrescine, and phosphatidylethanolamines and elevated alanine, leucine, phenylalanine, tryptophan, proline, glycine, lysine, serine, glutamate, cadaverine, and pyrophosphate. Thus, death by metabolic stress parallels cellular attempts to survive. Cleavage-dependent appearance of the C-terminal cationic amphipathic α-helix is inducible within hours by Staphylococcus epidermidis and slowly by another mechanism, in a chymotrypsin- or leupeptin protease-inhibitable manner. Although bactericidal at low micromolar levels, within a biphasic 1–10 nm dose optimum, the same domain is mitogenic and cytoprotective for epithelia via a syndecan-1 targeting mechanism dependent on heparanase. Thus, the C terminus of lacritin is multifunctional by dose and proteolytic processing and appears to play a key role in the innate protection of the eye, with wider potential benefit elsewhere as lacritin flows from exocrine secretory cells.

Sutureless cryopreserved amniotic membrane graft and wound healing after photorefractive keratectomy.

Purpose To evaluate the effect of sutureless cryopreserved amniotic membrane (Prokera) on corneal wound healing after photorefractive keratectomy (PRK). Setting Center for Refractive Surgery, Walter Reed Army Medical Center, Washington, DC, USA. Design Prospective nonrandomized control trial. Methods Patients had PRK for myopia with or without astigmatism. A 20% ethanol solution was used to create a standard 9.0 mm epithelial defect followed by photoablation with the Allegretto Wave Eye‐Q 400 Hz laser. After surgery, a high‐oxygen‐transmissible bandage contact lens (Acuvue Oasys) was applied on the dominant eye and cryopreserved amniotic membrane on the nondominant eye. The postoperative regimen was otherwise identical for both eyes. Postoperatively, patients were evaluated daily until complete corneal reepithelialization occurred in both eyes and then at 2 weeks and 1, 3, 6, and 12 months. Reepithelialization was assessed daily with slitlamp examination, fluorescein staining, and photography. Secondary outcome measures included adverse effects, ocular comfort, visual outcomes, and corneal haze. Results Forty patients were enrolled. The amniotic membrane graft sped corneal reepithelialization 1 day after PRK but was not better than the bandage contact lens in hastening complete reepithelialization of the cornea. Visual outcomes, corneal clarity, and optical quality of the cornea were comparable between the amniotic membrane graft eyes and bandage contact lens eyes. Conclusion Although the amniotic membrane graft was reasonably well tolerated with few significant adverse effects, the role of amniotic membrane in modulating wound healing after PRK remains speculative. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.

Residency training in refractive surgery.

PURPOSE: To evaluate resident refractive surgery caseload and surgical outcomes in an academic medical center. SETTING: Walter Reed Army Medical Center, Washington, DC, USA. DESIGN: Comparative case study. METHODS: Keratorefractive procedures performed by residents at the Walter Reed Center for Refractive Surgery between 2002 and 2010 were reviewed. Outcomes of surgeries performed by the graduating classes of 2008 to 2010 were compared with those of cases performed by staff. The uncorrected distance visual acuity (UDVA), manifest refraction spherical equivalent, corrected distance visual acuity (CDVA), and complications were analyzed. RESULTS: Between 2002 and June 2010, residents performed 1566 procedures (1414 photorefractive keratectomy [PRK], 152 laser in situ keratomileusis), for a mean of 20.2 procedures from 2002 to 2004, 51.6 from 2005 to 2007, and 99.9 from 2008 to 2010. Outcomes analysis was performed on 333 resident eyes and 977 staff eyes treated between 2008 and June 2010. Six months postoperatively, 96.1% of resident‐treated eyes and 94.6% of staff‐treated eyes had a UDVA 20/20 or better (P=.312) and 61.3% and 64.3%, respectively, had a UDVA 20/15 or better (P=.324). The percentage of eyes within ±0.50 diopter of emmetropia at 6 months was 94.0% for residents and 91.1% for staff (P=.105). The postoperative CDVA was within 2 lines of preoperative baseline in all resident cases and 99.8% of staff cases (P=.999). CONCLUSIONS: Resident experience grew steadily over the period studied. Overall safety and efficacy of resident‐performed surgery, albeit mainly PRK based, matched that of fellowship‐trained refractive surgeons. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Photorefractive keratectomy in posterior polymorphous dystrophy with vesicular and band subtypes

PURPOSE: To evaluate the safety and efficacy of photorefractive keratectomy (PRK) in patients with posterior polymorphous dystrophy (PPMD) with vesicular and band subtypes. SETTING: Walter Reed Center for Refractive Surgery, Washington, DC, USA. DESIGN: Case series. METHODS: The records of patients with PPMD who had PRK between January 2002 and May 2009 were reviewed. Data for analysis included sex, age, ablation depth, residual stromal bed thickness, manifest spherical equivalent, uncorrected (UDVA) and corrected (CDVA) distance visual acuities, central corneal thickness (CCT), endothelial cell density (ECD), intraocular pressure (IOP), and complications. Preoperative and postoperative results were compared using the Wilcoxon signed‐rank test, with P<.05 considered significant. RESULTS: Fourteen eyes of 7 men (mean age 29.1 years ± 9.1 [SD]; range 21 to 42 years) with at least a 6‐month follow‐up were reviewed. At the final follow‐up (mean 19.5 months; range 6.3 to 58.3 months), all eyes had a UDVA of 20/15 and all eyes were within ±0.50 diopter of emmetropia. The CDVA was unchanged from preoperatively in 71.4% of eyes and improved by 1 line in 28.6%. There were no significant complications. The IOP did not change significantly over the follow‐up (P=.272). At the final visit, the mean ECD (2795.3 ± 366.0 cells/mm2) was unchanged from baseline (2809.1 ± 338.3 cells/mm2) (P=.114). CONCLUSIONS: Photorefractive keratectomy in PPMD patients with vesicular and band subtypes resulted in excellent visual outcomes and a low incidence of adverse effects. Endothelial cell densities did not change significantly in the early postoperative period. Financial disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Goblet cell response after photorefractive keratectomy and laser in situ keratomileusis.

Purpose To determine whether patients without dry eye preoperatively have an altered conjunctival goblet cell density and mucin secretion postoperatively and to explore what factors affect changes in goblet cell density and mucin secretion. Setting The former Walter Reed Army Medical Center, Washington, DC, USA. Design Prospective nonrandomized clinical study. Methods Impression cytology was used to determine conjunctival goblet cell density before and 1 week, 1 month, and 3 months after photorefractive keratectomy (PRK) or laser in situ keratomileusis (LASIK). The McMonnies questionnaire, Schirmer test, tear breakup time, corneal sensitivity, rose bengal staining, and computerized videokeratoscopy were also performed to assess tear‐film and ocular‐surface health. Results The ratio of goblet cell to total cells changed postoperatively from baseline in both groups (P < .001). The most significant change was a median 29% decrease 1 month postoperatively. However, there were no significant differences between groups over time (P = .772). The ratio of filled goblet cell to total goblet cell did not change significantly over the same time period (P = .128), and there were no significant differences between the PRK group and the LASIK group over time (P = .282). Conclusions Patients without apparent dry eye had an altered conjunctival goblet cell population after PRK or LASIK. The conjunctival goblet cell population tended to decrease in the early postoperative period after either surgery and was most affected by preoperative goblet cell density. The changes in the tear film and ocular surface did not seem to affect goblet cell mucin secretion after either procedure. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.

Contrast Sensitivity After Wavefront-Guided and Wavefront-Optimized PRK and LASIK for Myopia and Myopic Astigmatism

PURPOSE To compare contrast sensitivity among participants undergoing wavefront-guided or wavefront-optimized photorefractive keratectomy (PRK) or LASIK for the treatment of myopia or myopic astigmatism 12 months after surgery. METHODS In a prospective, randomized clinical trial, 215 participants with myopia ranging from -0.50 to -7.25 diopters (D) and less than -3.50 D of manifest astigmatism electing to undergo either LASIK or PRK were randomized to receive wavefront-guided or wavefront-optimized treatment. Corrected Super Vision Test (Precision Vision, La Salle, IL) high contrast and small letter contrast sensitivity, uncorrected postoperative contrast sensitivity function, and uncorrected and corrected distance visual acuity were measured preoperatively and at 1, 3, 6, and 12 months postoperatively. RESULTS There was a significant difference within each of the four groups over time when measuring high contrast visual acuity (P < .001) and small letter contrast sensitivity (P < .001), with the most significant decrease occurring 1 month postoperatively. However, there were no significant differences when comparing the four groups for high contrast sensitivity (P = .22) or small letter contrast sensitivity (P = .06). The area under the logarithm of contrast sensitivity function did not differ significantly over time (P = .09) or between groups (P = .16). A pairwise comparison of preoperative to 12-month CDVA showed a significant improvement in all groups (P < .017). The change in CDVA was also significantly different between groups as determined by one-way analysis of variance (P = .003). CONCLUSIONS Wavefront-guided and wavefront-optimized PRK and LASIK procedures maintained high contrast, small letter contrast sensitivity, and contrast sensitivity function 12 months postoperatively. Although the recovery period for visual performance was longer for PRK versus LASIK, there was no significant difference in treatment type or treatment profile at 12 months postoperatively. [J Refract Surg. 2018;34(9):590-596.].

Vision-Related Quality of Life and Perception of Military Readiness and Capabilities Following Refractive Surgery Among Active Duty U.S. Military Service Members

PURPOSE To assess vision-related quality of life and military readiness and capabilities among active duty U.S. military service members undergoing refractive surgery. METHODS In this prospective, single-center, observational study, active duty U.S. military service members electing to undergo refractive surgery were asked to complete a military performance questionnaire and the National Eye Institute Refractive Error Quality of Life Instrument (NEI RQL-42) preoperatively and at 6 months postoperatively. On the military performance questionnaire, participants rated (1 = very bad to 5 = very good) how they felt their vision affected their military readiness and capabilities after refractive surgery. RESULTS Among 360 participants at 6 months postoperatively, the overall mean military performance score increased from 3.6 ± 0.8 to 4.8 ± 0.3, a change of 1.2, with 91.7% of the participants indicating an overall improvement in readiness and capability (P < .001). Scores measuring overall individual readiness, contribution to units mission, use of night vision goggles, function at night, weapons sighting ability, employment of personal masks, weather extreme environmental conditions, and optical support were significantly higher postoperatively (P < .001). For the NEI RQL-42, scores were significantly higher postoperatively for the subscales clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limit, glare, dependence on correction, worry, appearance, and satisfaction with correction (all P < .001), but not for symptoms after refractive surgery (P = .403). CONCLUSIONS Refractive surgery significantly improves military readiness and capabilities and vision-related quality of life of active duty U.S. military service members with refractive error. [J Refract Surg. 2018;34(9):597-603.].

Self-Reported Visual Quality of Life After Combat Ocular Trauma

OBJECTIVES To describe the visual outlook and quality of life of service members after combat ocular trauma. METHODS In a single-center, prospective observational study of service members sustaining ocular trauma, participants underwent a series of ocular examinations and noninvasive tests, including the National Eye Institute Visual Functioning Questionnaire (VFQ-25). RESULTS Of the 165 enrolled participants, 137 completed the VFQ-25. The mean VFQ-25 composite score was 74.4 ± 20.7 (range: 1.4-100). Among 118 participants with visual acuity assessment, 92% had best corrected visual acuity (BCVA) of 20/20 or better in at least one eye. Among participants with severe vision loss (BCVA ≤20/200), there was no statistically significant difference in self-reported general health compared to those without severe vision loss (p = 0.17). However, there was a significantly lower visual quality of life reported in the composite score and all of the 11 subscales of the VFQ-25. CONCLUSIONS While this study provides evidence that combat ocular trauma is associated with a lower visual quality of life, limitations include the relatively small sample size and the limited documentation of the use of eye protection at time of injury among participants.