Weldon W Haw

Late onset diffuse lamellar keratitis associated with an epithelial defect in six eyes.

PURPOSE To report six cases of late onset diffuse lamellar keratitis associated with epithelial defects 2 to 12 months following uncomplicated laser in situ keratomileusis (LASIK). METHODS Retrospective case series. RESULTS The interface inflammation and epithelial defects were treated aggressively with topical corticosteroids and topical antibiotics with complete resolution over 1 to 2 weeks. There were no complications or loss of best spectacle-corrected visual acuity. These cases illustrate new understanding in the etiology of diffuse lamellar keratitis following lamellar surgery. CONCLUSION Late onset diffuse lamellar keratitis in association with epithelial defects may occur following LASIK. Treatment with topical antibiotics and topical corticosteroids may result in uncomplicated, complete resolution.

Effect of preoperative pupil measurements on glare, halos, and visual function after photoastigmatic refractive keratectomy

Purpose: To prospectively assess the effect of preoperative variables such as pupil size on glare, halos, and visual function after photoastigmatic refractive keratectomy (PARK). Setting: Department of Ophthalmology, Stanford University School of Medicine, Stanford, California, USA. Methods: Ninety‐three eyes had PARK for primary compound myopic astigmatism. Preoperative pupil diameters were measured under scotopic and photopic illuminance conditions. Postoperatively, patients were evaluated at 1, 3, 6, 9, 12, 18, and 24 months. A regression model was performed to evaluate the predictive value of assessing preoperative variables such as pupil diameter on the development of glare and halos, contrast sensitivity, and best spectacle‐corrected visual acuity (BSCVA) under scotopic, photopic, and glare conditions. Results: The greater magnitude loss of BSCVA under scotopic conditions in the early postoperative period as well as the slower recovery to preoperative levels in eyes with larger scotopic pupil diameters were not statistically significant (P gt; .05). An increase in symptoms of glare was related more to the attempted level of spherical equivalent (SE) correction than to the pupil size during the first 12 postoperative months (P < .01). The photoablation dimensions as determined by the attempted level of astigmatic correction may result in decreases in the glare BSCVA up to 12 months after PARK (P = .03). At the 2 year follow‐up, pupil diameter under both scotopic and photopic illuminance conditions was not predictive of any of the measured outcomes variables. Conclusions: An assessment of preoperative pupil size and the attempted level of both SE and astigmatic correction may be useful in identifying patients at risk of developing symptoms or declines in visual performance after PARK. However, follow‐up studies are indicated to identify variables predictive of poor visual outcomes following excimer laser refractive surgery.

Treatment of Progressive or Recurrent Epithelial Ingrowth With Ethanol Following Laser in situ Keratomileusis

PURPOSE To evaluate the use of ethanol in the treatment of progressive or recurrent epithelial ingrowth following laser in situ keratomileusis (LASIK). METHODS Four eyes of four patients with aggressive epithelial ingrowth following LASIK underwent epithelial ingrowth removal with 50% ethanol. Aggressive epithelial ingrowth was defined as, 1) progressive enlargement on serial examination with an area of ingrowth involving at least 30% of the flap surface area, 2) epithelial ingrowth associated with stromal melting as evidence on clinical or topographic examination, or 3) recurrent epithelial ingrowth in the same area following previous removal. RESULTS Epithelial ingrowth was removed successfully in all eyes. No eye lost best spectacle-corrected visual acuity. One eye with multiple risk factors for failure experienced nonprogressive recurrence. No eyes required reoperation for recurrent epithelial ingrowth. No eyes experienced progression of stromal melt. Regularization of corneal topography was observed in an eye with preoperative stromal melting. The only complication was a tendency for the development of diffuse lamellar keratitis. Two eyes (50%) experienced diffuse lamellar keratitis following epithelial ingrowth removal with ethanol, which resolved completely with topical corticosteroids. CONCLUSION Ethanol may be a useful adjunct in the treatment of aggressive or recurrent epithelial ingrowth following LASIK. Cautious use with the lowest concentration of ethanol may prove useful in these difficult epithelial ingrowth cases. Randomized and prospective studies are recommended to evaluate our experience.

Iatrogenic keratectasia after a deep primary keratotomy during laser in situ keratomileusis

PURPOSE To describe a case of keratectasia after a deep primary keratotomy during an aborted laser in situ keratomileusis procedure. METHODS Retrospective, observational case report. RESULTS In a 47-year-old woman, progressive keratectasia developed after a 90% depth keratotomy during an aborted laser in situ keratomileusis procedure. This case was managed with a rigid gas permeable contact lens and consideration for penetrating keratoplasty. CONCLUSION Keratectasia is a reported microkeratome-related complication after laser in situ keratomileusis. Appropriate microkeratome assembly and surgeon awareness are necessary to avoid this complication.

Sterile peripheral keratitis following laser in situ keratomileusis

BACKGROUND Sterile infiltrates have been reported as a possible complication following photorefractive keratectomy (PRK). They have not been reported following laser in situ keratomileusis (LASIK). We review a case of fleeting, sterile peripheral corneal infiltrates following LASIK. METHODS A 53 year old patient developed peripheral, sterile corneal infiltrates along the edge of the primary flap following LASIK. This was successfully managed with topical antibiotics and corticosteroids without permanent sequelae. RESULTS Sterile peripheral corneal infiltrates are now a known complication following LASIK. Pathogenesis is undetermined but may involve activation of marginal keratitis reminiscent of that following blepharitis or a mechanism similar to acute subepithelial infiltrative keratitis following PRK. CONCLUSION Fleeting, sterile peripheral corneal infiltrates can occur following LASIK. This undesired complication is poorly characterized but can be successfully managed with culturing of the infiltrates, topical corticosteroids, and antibiotics.

Laser in situ keratomileusis enhancement for consecutive hyperopia after myopic overcorrection

Purpose: To assess the efficacy, predictability, and safety of laser in situ keratomileusis (LASIK) for the treatment of consecutive hyperopia after myopic LASIK. Setting: Stanford University School of Medicine, Stanford, California, USA. Methods: In a retrospective study, 36 eyes of 30 patients with consecutive hyperopia after myopic LASIK had LASIK retreatment using the VISX S2 excimer laser. Primary outcome variables including uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity (BSCVA), manifest refraction, complications, and vector analysis were evaluated preoperatively and 1 day and 3 months postoperatively. Results: The mean spherical equivalent decreased from +1.52 diopters (D) ± 0.55 (SD) (range +0.63 to +2.63 D) preoperatively to −0.10 ± 0.52 D (range −1.25 to +1.50 D) 3 months after retreatment. The UCVA was 20/20 or better in 24 eyes (66.7%) and 20/40 or better in 34 eyes (94.4%). Twenty eyes (55.5%) were within ±0.5 D of the intended correction and 34 eyes (94.4%), within ±1.0 D. No eye lost 2 or more lines of BSCVA. One eye (2.8%) developed diffuse lamellar keratitis that resolved without sequelae, and 2 eyes (5.6%) developed nonprogressive epithelial ingrowth that did not require removal. Conclusions: Laser in situ keratomileusis retreatment for consecutive hyperopia following myopic LASIK was an effective, predictable, and safe procedure. Long‐term follow‐up is needed to assess stability.

Conductive keratoplasty and laser thermal keratoplasty.

Recent innovations in refractive surgery technology have emphasized the reshaping of the cornea through nonincisional and nonlamellar methods to achieve controlled, accurate, and reproducible refractive effects. Unlike those with excimer laser ablative procedures, such as photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK), many potentially vision-threatening complications can be minimized by avoiding surgical manipulation of the visual axis and by preserving (not ablating or removing) corneal tissue. This chapter will review the principles, clinical results, and applications of using these new noninvasive refractive surgery modalities that promote collagen fiber shrinkage within the peripheral cornea in evolving procedures labeled laser thermal keratoplasty (LTK) and conductive keratoplasty (CK).

Excimer laser retreatment of residual myopia following photoastigmatic refractive keratectomy for compound myopic astigmatism

PURPOSE To prospectively evaluate the safety, efficacy, and visual performance of excimer laser enhancement following photoastigmatic refractive keratectomy (PARK) with the Summit Apex Plus. SETTING Stanford University School of Medicine Eye Laser Clinic, Stanford, California, USA. METHODS As part of a Food and Drug Administration clinical trial, 93 eyes of 56 patients with a mean spherical equivalent (SE) of -4.98 diopters (D) +/- 1.80 (SD) (range -1.75 to -8.50 D) had PARK for compound myopic astigmatism using the Summit Apex Plus excimer laser and a poly(methyl methacrylate) erodible mask. Seventeen eyes with a mean SE of -2.08 +/- 0.76 D required excimer laser refractive keratectomy for residual spherical myopia or compound myopic astigmatism. Patients were prospectively followed 1, 3, 6, 9, and 12+ months after the enhancement procedure. Primary outcome variables included uncorrected visual acuity (UCVA), refraction, vector analysis, best spectacle-corrected visual acuity (BSCVA) under standard ambient conditions (photopic, scotopic, and glare), corneal clarity, and contrast sensitivity function curve under photopic and scotopic conditions. RESULTS At the last postoperative visit, the mean sphere had been corrected 82% to a residual of -0.29 +/- 1.23 D and mean SE had been corrected 65% to a residual of -0.74 +/- 1.27 D. Eighty-two percent of eyes were within +/-1.0 D of attempted correction. Eighty-eight percent had a UCVA of 20/40 or better. Vector analysis demonstrated a difference vector of within +/-1.0 D in 75% of eyes that had PARK retreatment. There was no significant loss in the contrast sensitivity curve. Late regression associated with corneal haze and loss of BSCVA occurred in 2 eyes (11.7%). CONCLUSIONS Retreatment following PARK for compound myopic astigmatism results in effective reduction in residual spherical myopia and compound myopic astigmatism. An improvement in UCVA without loss of contrast sensitivity can be expected in most eyes. However, regression, corneal haze, and loss of BSCVA may occur. Further studies are indicated to predict risk factors for these complications.

Photorefractive keratectomy for compound myopic astigmatism

PURPOSE To evaluate the safety and efficacy of photorefractive keratectomy for the treatment of primary compound myopic astigmatism. METHODS In a prospective study, 93 eyes from 56 patients with a mean spherical equivalent of -4.98 +/- 1.80 diopters (range, -1.75 to -8.5) underwent photoastigmatic refractive keratectomy with the Summit Apex Plus excimer laser using erodible mask technology and were followed for 2 years. Primary outcome measures included an assessment of astigmatic correction through vector analysis, manifest refraction, uncorrected visual acuity, corneal clarity, and the presence of adverse symptoms. RESULTS Eighty-five eyes (91.4%) were available for analysis at 6 months. Mean spherical equivalent refraction was reduced 85% (mean, -0.75 +/- 0.85 diopter) and the target-induced astigmatism was reduced 70% (mean, 0.98 +/- 1.88 diopters). Forty-eight eyes (56%) had an uncorrected visual acuity of 20/20 or greater, whereas 70 eyes (82%) had an uncorrected visual acuity of 20/40 or greater. Twenty-four eyes (26% ) required re-treatment because of undercorrection of the spherical equivalent and astigmatic components after the 6-month follow-up. Fifty-nine of the remaining eyes were available at the 24-month visit. Mean spherical equivalent refraction was reduced to -0.39 +/- 0.72 diopter (91.8%). The target-induced astigmatism was reduced 64% from 1.74 diopters. Forty-one eyes (81.3%) were within +/-1.0 diopter of attempted spherical equivalent correction. Stability within a spherical equivalent of +/-0.5 diopter occurred after the first postoperative month. Fifty-six eyes (94.9%) had an uncorrected visual acuity of 20/40 or greater, whereas 34 eyes (57.6 %) demonstrated an uncorrected visual acuity of 20/20 or greater. One eye (1.7%) lost 2 or more lines of best spectacle-corrected visual acuity. CONCLUSION Photoastigmatic refractive keratectomy with the Summit Apex Plus excimer laser is a safe and effective method of reducing compound myopic astigmatism. However, higher re-treatment rates may result from significant undercorrections because of current laser algorithms and variability in the mean angle of error.

Large optical ablation zone using the VISX S2 smoothscan excimer laser.

Purpose: To prospectively evaluate the safety and efficacy of the new large‐zone (6.5 mm) photoablation technology using the VISX S2 Smoothscan excimer laser. Setting: University‐based hospital, Stanford, California, USA. Methods: Forty‐two eyes of 21 patients with a mean preoperative spherical equivalent (SE) of−5.55 diopters (D)± 2.24 (SD) (range−2.13 to−10.75 D) had laser in situ keratomileusis (LASIK) using the VISX Smoothscan S2 excimer laser for simple myopia or compound myopic astigmatism. A 6.5 mm optical zone was used in all eyes. Patients were prospectively followed 1 day and 1 and 3 months postoperatively. Results: At 3 months, the mean SE was reduced 94% to−0.31± 0.55 D. Ninety‐one percent of eyes had an uncorrected visual acuity of 20/40 or better. Eighty‐eight percent were within±1.00 D of attempted correction and 84%, within ±0.50 D. Stability within±0.50 D occurred after the first postoperative month. Vector analysis of eyes that had toric ablations demonstrated a difference vector within±1.00 D in 100% of eyes. The mean angle of error was−0.04± 6.37 degrees. Visually significant steep central islands associated with loss of best spectacle‐corrected visual acuity was observed in 7.5% of eyes at 1 month. No eyes experienced significant glare or halos. Conclusions: The new large‐zone (6.5 mm) photoablation technology with the VISX S2 Smoothscan resulted in effective reduction of simple myopia and compound myopic astigmatism. However, with the 6.5 mm zone, there may be an increased risk of developing symptomatic steep central islands in the early post‐LASIK period compared with the standard 6.0 mm treatment zone.