Aristofanis I. Pallikaris

Induced optical aberrations following formation of a laser in situ keratomileusis flap

Purpose: To determine how refractive error, visual acuity, and high‐order aberrations (3rd‐ and 4th‐order) are affected by the formation of a lamellar corneal flap during laser in situ keratomileusis (LASIK). Setting: University refractive surgery center. Methods: The effect of lamellar corneal flap formation was analyzed in 15 myopic eyes (mean preoperative refraction −4.72 diopters [D] [range −1.25 to −7.25 D]). The flap was created using a 2‐step procedure: (1) a nasally hinged lamellar corneal flap was created; (2) the flap was lifted and stromal ablation performed 2 months after the flap was made. A Hartmann‐Shack aberrometer was used to measure the aberrations. Results: There was no significant change in the refractive error (spherical equivalent pre‐flap −4.72 ± 1.99 D and post‐flap −4.62 ± 1.99 D [P = .28]) or visual acuity (pre‐flap uncorrected visual acuity [UCVA] 0.07 and best corrected visual acuity [BCVA] 0.96; post‐flap UCVA 0.08 and BCVA 0.95 [P = .16 and P = .33, respectively]). A statistically significant increase in total higher‐order wavefront aberrations was observed following flap formation (root mean square pre‐flap 0.344 ± 0.125 and post‐flap 0.440 ± 0.221 [P = .04]). Conclusion: Flap formation during LASIK can modify the eyes existing natural higher‐order aberrations (especially spherical and coma‐like aberrations along the axis of the flaps hinge), while visual acuity and refractive error remain unaffected.

Eleven-year follow-up of laser in situ keratomileusis.

PURPOSE: To report the long‐term (11‐year) outcomes (stability and complications) of laser in situ keratomileusis (LASIK) in patients with high myopia. SETTING: University refractive surgery center. METHODS: Seven patients (4 with bilateral treatment and 3 with unilateral treatment) who had myopic LASIK and completed 11 years of follow‐up were included in the study. RESULTS: The mean age of the 2 men and 5 women was 41.7 years ± 6.5 (SD) (range 34 to 50 years). The mean follow‐up was 140.18 ± 6.70 months (range 132 to 150 months). At 11 years, the spherical equivalent error was statistically significantly reduced, from a mean of −12.96 ± 3.17 diopters (D) (range −19.00 to −10.00 D) before LASIK to a mean of −1.14 ± 1.67 D (range −4.25 to 1.00 D) after (P<.001). Predictability of postoperative refraction 6 months and 11 years after LASIK showed that 6 eyes (55%) were within ±1.00 D of intended correction. No late postoperative complications occurred. Five patients (8 eyes, 73%) were satisfied with the final outcome. CONCLUSIONS: Laser in situ keratomileusis was moderately predictable in the correction of high degrees of myopia. After the sixth postoperative month, refractive and topographic stability were obtained. No long‐term sight‐threatening complications occurred during the follow‐up period.

Posterior Linear Stromal Haze Formation after Simultaneous Photorefractive Keratectomy followed by Corneal Collagen Cross-linking

PURPOSE To report the development of posterior linear stromal haze after simultaneous photorefractive keratectomy (PRK) followed by corneal collagen cross-linking (CXL). METHODS Combined simultaneous customized PRK followed by corneal collagen cross-linking was performed in 23 patients (28 eyes) with keratoconus. Corneas were examined biomicroscopically and by means of confocal microscopy before surgery and 1, 3, 6, 9, and 12 months after surgery. RESULTS Posterior linear stromal haze was observed clinically (slit lamp biomicroscopy) one month after surgery in 13 of 28 eyes (46.42%). No corneal edema or anterior haze formation was evident. Confocal microscopy revealed in those 13 eyes a hyperreflective area at the level of the posterior stroma 1 month after combined treatment. Both slit lamp examination and corneal confocal microscopy follow-up demonstrated a gradual anterior movement and a decrease in reflectance of this finding. At 12 months this posterior linear stromal haze, despite its anterior movement and decreased density, did not completely disappear at slit lamp and confocal microscopy analysis. CONCLUSIONS Posterior linear stromal haze formation may appear after simultaneous PRK followed by CXL in patients with keratoconus. This finding seems to gradually become less dense and slowly moves toward the anterior stroma.

One-year results of photorefractive keratectomy and laser in situ keratomileusis for myopia using a 213 nm wavelength solid-state laser

PURPOSE: To study the long‐term results of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) in low to moderate myopic corrections using the Pulzar Z1 system (CustomVis), a 213 nm wavelength solid‐state laser. SETTING: University refractive surgery center. METHODS: This prospective noncomparative case series comprised 20 patients (40 eyes) who had refractive surgery using the Pulzar Z1 laser system. Manifest refraction, uncorrected visual acuity, best spectacle‐corrected visual acuity (BSCVA), safety, predictability, stability, and confocal microscopy images were evaluated. RESULTS: Ten patients (20 eyes) had PRK and 10 patients (20 eyes) had LASIK. The mean follow‐up was 13.9 months ± 1.1 (SD) (range 12 to 17 months) and 14.6 ± 1.2 months (range 12 to 18 months) in the PRK group and LASIK group, respectively. No eye lost a line of Snellen BSCVA during the follow‐up period; 2 eyes (10%) gained 2 Snellen lines. There was a statistically significant decrease in spherical equivalent manifest refraction postoperatively in both groups (P<.05). Refractive stability was obtained during the first postoperative month and remained stable during the follow‐up period, with no significant changes between any interval in both groups (P>.05). At the last follow‐up, 95% of all eyes were within ±1.00 diopter of emmetropia. No late postoperative complications were observed. CONCLUSION: Refractive surgery using the Pulzar Z1 213 nm wavelength solid‐state laser was a safe, effective procedure in the treatment of low to moderate myopia.

Endothelial cell density after photorefractive keratectomy for moderate myopia using a 213 nm solid-state laser system

PURPOSE: To evaluate whether photorefractive keratectomy (PRK) for moderate myopia using a solid‐state laser with a wavelength of 213 nm alters the corneal endothelial cell density. SETTING: University refractive surgery center. METHODS: The corneal endothelium was analyzed preoperatively and 1, 6, and 12 months postoperatively using corneal confocal microscopy (modified HRT II with a Rostock Cornea Module, Heidelberg Engineering) in 60 eyes (30 patients). Patients were randomized to have myopic PRK using a 213 nm wavelength solid‐state laser (study group) or a conventional 193 nm wavelength excimer laser (control group). Three endothelial images were acquired in each of 30 preoperative normal eyes to evaluate the repeatability of endothelial cell density measurements. Repeated‐measures analysis of variance was used to compare the variations in endothelial cell density between the 2 lasers and the changes in endothelial cell density over time. RESULTS: There were no statistically significant differences in sex, age, corneal pachymetry, attempted correction, preoperative endothelial cell density, or postoperative refractive outcomes (uncorrected visual acuity, best spectacle‐corrected visual acuity, and spherical equivalent refraction) between the 2 groups (P>.05). The coefficient of repeatability of endothelial cell density was 131 cells/mm2. The measured endothelial cell count per 1.0 mm2 did not significantly change up to 1 year postoperatively in either group (both P>.05). No statistically significant difference was found between the 2 groups in any postoperative interval (P>.05). CONCLUSION: Photorefractive keratectomy for moderate myopia using a 213 nm wavelength solid‐state laser or a conventional 193 nm wavelength excimer laser did not significantly affect corneal endothelial density during the 1‐year postoperative period.

Nine-year follow-up of intacs implantation for keratoconus.

Purpose: To present a case of nine- year bilateral Intacs (Addition Technology, Inc, Fremont, California, USA) implantation for early stage keratoconus. Methods: A 25-year-old male underwent bilateral Intacs implantation for the management of keratoconus and hardcontact-lens intolerance (stage 1) in 1999. Results: Nine years postoperatively, spherical equivalent refraction changed from preoperative -0.75 and -2.25 to +0.75 and –1.25 for the right and the left eye, respectively. UCVA was improved from 20/50 to 20/25 in the right and from 20/200 to 20/32 in the left eye. BSCVA of 20/20 in the right eye maintained stable in comparison with the Pre-Intacs BSCVA, while BSCVA was improved from 20/25 to 20/20 in the fellow eye. No early or late complications were observed. Conclusions: Nine years after bilateral Intacs implantation for the management of early stage keratoconus, there was a significant improvement and postoperative stability in patient’s visual acuity. No long-term, sight-threatening complications were identified during follow-up.

Nine-year Follow-up of a Posterior Chamber Phakic IOL in One Eye and LASIK in the Fellow Eye of the Same Patient

PURPOSE To compare the long-term results (9 years) of LASIK in one eye and phakic intraocular lens (implantable contact lens [ICL]) implantation in the fellow eye of the same patient. METHODS A patient with high myopia underwent LASIK with a MEL 60 excimer laser in one eye (spherical equivalent refraction -9.75 diopters [D], 5-mm optical zone with no transition zone) and phakic intraocular lens (STAAR Collamer implantable contact lens [ICL]) implantation (spherical equivalent refraction -9.50 D) in the fellow eye. RESULTS At 9 years postoperatively, the mean spherical equivalent refraction was -1.00 in the eye with the ICL and -1.75 D in the eye that underwent LASIK. During the first 6 postoperative months in the LASIK eye, refraction regressed, but remained stable during the remainder of follow-up. Uncorrected visual acuity was 20/25 in the eye with the ICL and 20/30 in the LASIK eye, whereas best spectacle-corrected visual acuity was 20/20 in both eyes. Less night vision problems (glare and halos) were experienced in the eye with the ICL compared to the LASIK eye. Although the patient initially preferred the LASIK procedure, at last follow-up 9 years postoperatively, increased overall satisfaction was reported for the eye with the ICL compared to the LASIK eye. CONCLUSIONS Nine years after treatment of high myopia with the ICL and LASIK in the same patient, better quality of vision, stability, and satisfaction score were achieved in the eye with the ICL compared to the eye that had undergone LASIK. No long-term sight-threatening complications were found during followup.

Long-term results of superficial laser in situ keratomileusis after ultrathin flap creation

PURPOSE: To study the long‐term efficacy, safety, and stability of laser in situ keratomileusis (LASIK) after unintentional ultrathin flap creation less than 80 μm. SETTING: University refractive surgery center. METHODS: This retrospective case series comprised 25 patients (33 eyes) who had LASIK after flap creation less than 80 μm with the Moria M2 disposable microkeratome (head 90 μm). Flap thickness was measured with intraoperative ultrasound pachymetry. Manifest refraction, uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity, predictability, stability, complications, patient satisfaction, and confocal microscopy images were studied. RESULTS: The mean follow‐up was 14.58 months ± 3.73 (SD) (range 12 to 25 months). The mean flap thickness was 72.1 ± 5.9 μm (range 58 to 80 μm), and the mean preoperative spherical equivalent (SE) refraction was –5.59 ± 2.01 diopters (D) (range −10.25 to −3.25 D). On the first postoperative day, the UCVA was 20/25 or better. The SE manifest refraction was 1.00 D or less in all patients. The mean SE manifest refraction was −0.75 ± 0.55 D (range −1.00 to +0.75 D) (P<.01). At the last follow‐up, changes in visual acuity and manifest refraction were not statistically significant; no late postoperative complications were observed. All patients were satisfied with the final outcome. Qualitative analysis of confocal microscopy images revealed interface particles and activated keratocytes. CONCLUSIONS: Despite the small sample and retrospective nature of the study, superficial LASIK seemed to be a safe and predictable technique for myopic refractive corrections. Patients were satisfied with the results and had rapid visual recovery with no intraoperative or early or late postoperative complications. If the safety and efficacy of an ultrathin flap are confirmed by additional studies, superficial LASIK could represent a new approach that combines the advantages of surface and lamellar procedures.

Idiopathic recurrence of diffuse lamellar keratitis after LASIK.

PURPOSE To report a case of late recurrence of bilateral diffuse lamellar keratitis (DLK) after LASIK. METHODS A 39-year-old woman presented in the early postoperative period with bilateral DLK after hyperopic LASIK and was treated with topical steroids. One year after and with no obvious cause (idiopathic), recurrence of the same stage (stage III) of disease was observed. RESULTS Slit-lamp examination revealed diffuse, multifocal, and granular haze in the interface. The microbiology culture was negative. Confocal microscopy demonstrated multiple activated keratocytes, debris, and inflammatory cells adjacent to the flap interface. After intense treatment with topical corticosteroids, DLK resolved and corneal transparency was achieved with complete restoration of visual acuity. CONCLUSIONS Diffuse lamellar keratitis may recur in LASIK patients with previous episodes without an obvious cause (idiopathic). Early diagnosis and treatment with topical corticosteroids can achieve complete resolution without visual loss--even in advanced stages of DLK.

Anterior Segment Applications of In Vivo Confocal Microscopy

ABSTRACT Purpose: To review the current literature on in vivo confocal microscopy anterior segment applications (cornea, conjunctiva, and glaucoma) and discuss its advantages in different pathological conditions. Methods: Review of selected relevant literature on in vivo confocal microscopy and its different applications. Results: In vivo confocal microscopy can be used to visualize most layers of the cornea and conjunctiva, providing excellent resolution. In the past, it was mainly utilized as a research tool; lately there seems to be an increasing interest for clinical applications; confocal microscopy aids the diagnosis and follow-up of many anterior segment disorders, such as corneal dystrophies, corneal and conjunctival inflammatory and neoplastic diseases, glaucoma patients, and assessment of surgical procedures. Conclusion: In vivo confocal microscopy is an important addition to the ophthalmic diagnostic tools with several anterior segment applications. Its clinical applications are being continuously explored and are quickly expanding to cover many new pathological aspects.