Michael Lawless

Progressive post-LASIK keratectasia: biomechanical instability or chronic disease process?

&NA; Progressive post‐LASIK keratectasia (PPLK) is a progressive deformation of corneal anatomy that occurs rarely but may have severe consequences. Using the scientific literature and new hypotheses, we attempted to determine whether PPLK is a biomechanical result of laser in situ keratomileusis (LASIK), a chronic disease process affecting individuals predisposed to the condition, or a combination of processes. We look at whether the combination of fatigue, specifically a form of dynamic fatigue, and proteolysis provides an environment conducive to the occurrence and progression of PPLK. This review may raise more questions than it answers and in so doing may move us toward a better understanding of this occasionally serious consequence of LASIK.

Penetrating Keratoplasty for Keratoconus

A series of 86 penetrating keratoplasties for keratoconus were analyzed. The surgery, using an 8.2 mm donor cornea into an 8.0 mm recipient opening, was performed over the period January 1983 to January 1986 by one surgeon. The donor cornea was secured by two opposing continuous sutures, placed at full corneal thickness under surgical keratometry control. Both sutures were removed at an average 30 weeks after surgery. The mean postoperative sutures-out astigmatism was 5.4 diopters (range 0-19.0 diopters) and following secondary astigmatism surgery in 17 eyes, the mean group astigmatism was 4.3 diopters (range 0-10.5 diopters). Although graft reaction occurred in 11.6% of cases it was cleared medically and did not affect final vision results. One month after suture removal, with spectacle correction, 45.5% of the primary group saw 20/20, 90.7% 20/30 or better, and 97.7% 20/40 or better. Comparing these results with recently published data on epikeratophakia for the treatment of keratoconus, it is evident that penetrating keratoplasty offers these usually young patients a better chance for recovery of useful industrial acuity.

LASIK for post penetrating keratoplasty astigmatism and myopia

AIMS To report the results of a series of patients who were treated with LASIK to correct post penetrating keratoplasty ametropia. METHODS 26 eyes of 24 patients underwent LASIK to correct astigmatism and myopia after corneal transplantation; 14 eyes also received arcuate cuts in the stromal bed at the time of surgery. The mean preoperative spherical equivalent was −5.20D and the mean preoperative astigmatism was 8.67D. RESULTS The results of 25 eyes are reported. The mean 1 month values for spherical equivalent and astigmatism were −0.24D and 2.48D respectively. 18 eyes have been followed up for 6 months or more. The final follow up results for these eyes are −1.91D and 2.92D for spherical equivalent and astigmatism. The patients undergoing arcuate cuts were less myopic but had greater astigmatism than those not. The patients receiving arcuate cuts had a greater target induced astigmatism, surgically induced astigmatism, and astigmatism correction index than those eyes that did not. One eye suffered a surgical complication. No eyes lost more than one line of BSCVA and all eyes gained between 0 and 6 lines UCVA. CONCLUSIONS LASIK after penetrating keratoplasty is a relatively safe and effective procedure. It reduces both the spherical error and the cylindrical component of the ametropia. Correction of high astigmatism may be augmented by performing arcuate cuts in the stromal bed.

Capsular block syndrome associated with femtosecond laser-assisted cataract surgery.

UNLABELLED We report intraoperative capsular block syndrome occuring during the first 50 femtosecond laser-assisted cataract surgeries performed in our facility. Two patients had uneventful combined laser fragmentation, capsulotomy, and corneal incision procedures. In both cases, following transfer to the operating room and manual removal of the laser-cut capsulotomy, posterior capsule rupture was noted during hydrodissection, resulting in posterior dislocation of the lens. Pars plana vitrectomy, removal of the crystalline lens, and sulcus implantation of an intraocular lens were performed in both patients with good visual outcomes. Femtosecond laser-assisted cataract surgery changes the intraoperative environment with the generation of intracapsular gas and laser-induced changes in the cortex. With awareness of the changed intraocular environment following laser lens fragmentation and capsulotomy and a modification of the surgical technique, no additional cases of intraoperative CBS have been seen in more than 600 laser-assisted cataract surgery procedures performed to date at our facility. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes.

Staphylococcal infection under a LASIK flap

PURPOSE To report a staphylococcal infection under a laser in situ keratomileusis (LASIK) flap and to discuss the management of this rare and potentially devastating complication. METHODS A patient was referred to our practice having had bilateral LASIK. She was found to have abscesses under the left corneal flap. Staphylococcus aureus was identified as the infecting organism by corneal scrape and treated with appropriate antibiotics. The cornea improved, and then the abscess recurred. The abscess was again scraped and intensive treatment reinstituted. RESULTS After successful treatment, the patient recovered excellent visual acuity with only a minimal astigmatic error. CONCLUSION The possible reasons for the apparent improvement and then recurrence of the abscess are discussed. The management of this case including the need for corneal scrape and antibiotic prophylaxis is discussed in relation to previously reported cases.

Intraocular Lens Power Calculation for Cataract Surgery after Photorefractive Keratectomy for High Myopia

OBJECTIVE To assess intraocular lens (IOL) power calculations in patients undergoing cataract surgery after excimer laser photorefractive keratectomy (PRK) for myopia. METHODS Four eyes of two patients underwent phacoemulsification with IOL implantation after PRK for myopia. The estimated refractive error that would have been induced had the IOL predicted for emmetropia been implanted was calculated using SRK-II, SRK/T, Holladay, and Binkhorst formulas. Manual keratometry and videokeratography-simulated keratometry values measured before surgery were used. Keratometry values calculated by subtracting the refractive change induced by the excimer laser PRK from the manual keratometry or videokeratography-simulated keratometry values measured before PRK were also used. Both spectacle and corneal plane calculations were performed. RESULTS Manual keratometry and videokeratography-simulated keratometry values underpredicted the IOL power. Corneal plane manual or videokeratography refraction-derived keratometry calculations were most accurate using the SRK/T formula, while spectacle plane calculations were most accurate using the SRK-II formula. In both methods the calculated refractive error was within 0.52 diopters (D) for the emmetropic lens power predicted. Statistical analysis was not performed. CONCLUSIONS Refraction-derived keratometric values provided the most accuracy in calculating IOL powers. Our results suggest the SRK/T formula was the most accurate for corneal plane calculations, while the SRK-II formula was the most accurate for spectacle plane calculations.

Femtosecond laser cataract surgery: technology and clinical practice

The recent introduction of femtosecond lasers to cataract surgery has generated much interest among ophthalmologists around the world. Laser cataract surgery integrates high‐resolution anterior segment imaging systems with a femtosecond laser, allowing key steps of the procedure, including the primary and side‐port corneal incisions, the anterior capsulotomy and fragmentation of the lens nucleus, to be performed with computer‐guided laser precision. There is emerging evidence of reduced phacoemulsification time, better wound architecture and a more stable refractive result with femtosecond cataract surgery, as well as reports documenting an initial learning curve. This article will review the current state of technology and discuss our clinical experience.The recent introduction of femtosecond lasers to cataract surgery has generated much interest among ophthalmologists around the world. Laser cataract surgery integrates high-resolution anterior segment imaging systems with a femtosecond laser, allowing key steps of the procedure, including the primary and side-port corneal incisions, the anterior capsulotomy and fragmentation of the lens nucleus, to be performed with computer-guided laser precision. There is emerging evidence of reduced phacoemulsification time, better wound architecture and a more stable refractive result with femtosecond cataract surgery, as well as reports documenting an initial learning curve. This article will review the current state of technology and discuss our clinical experience.

Outcomes of Femtosecond Laser Cataract Surgery With a Diffractive Multifocal Intraocular Lens

PURPOSE To report the visual and refractive outcomes in an initial series of eyes undergoing femtosecond laser cataract surgery with implantation of a diffractive multi-focal intraocular lens (IOL). METHODS The first 61 consecutive eyes undergoing femtosecond laser cataract surgery and ReSTOR (Alcon Laboratories Inc) +3.00-diopter (D) add IOL implantation between May and July 2011 were enrolled in the study (LCS group). The control group consisted of a retrospective consecutive cohort of 29 eyes that underwent manual phacoemulsification cataract surgery and ReSTOR +3.00-D add IOL implantation (MCS group) between December 2010 and April 2011. Visual and refractive parameters were collected pre- and postoperatively at 1 and 3 months. RESULTS Mean postoperative spherical equivalent refraction was -0.01±0.35 D and -0.06±0.30 D in the LCS and MCS groups, respectively (P=.492). Mean absolute refractive prediction error (PE) was 0.26±0.25 D for the LCS group and 0.23±0.16 D for the MCS group (P=.489). Mean arithmetic refractive PE was 0.06±0.44 D and -0.02±0.30 D for the LCS and MCS groups, respectively (P=.388). No significant difference was noted in mean postoperative uncorrected distance visual acuity or uncorrected near visual acuity between groups. No eyes in either group had surgical complications or loss of corrected distance visual acuity in the follow-up period. CONCLUSIONS Mean spherical equivalent refraction and visual acuity of our initial group of patients undergoing laser cataract surgery are comparable to the manual phacoemulsification cohort for the AcrySof ReSTOR +3.00-D add IOL.

Recutting the Cornea Versus Lifting the Flap: Comparison of Two Enhancement Techniques Following Laser in situ Keratomileusis

PURPOSE To evaluate enhancement techniques following laser in situ keratomileusis (LASIK). METHODS Recutting was performed on 263 eyes and the flap was lifted in 55 eyes that had LASIK for simple myopia or myopic astigmatism. The time interval between LASIK and retreatment was 340+/-46 days (range, 270 to 892 days) in the recutting group and 215+/-36 days (range, 53 to 617 days) in the flap lifting group. Mean spherical equivalent refraction, refractive cylinder, uncorrected and best spectacle-corrected visual acuity were examined prior to, and 1, 3, and 6 months after retreatment. RESULTS Seventeen eyes were lost to follow-up in the lifting group and 53 eyes in the recutting group. In the recutting group, mean spherical equivalent refraction improved from -1.48+/-1.25 D to -0.49+/-0.88 D at 6 months. In the flap lifting group, mean spherical equivalent refraction improved from -1.05+/-1.49 D to -0.45+/-0.39 D at 6 months. Refractive cylinder did not change significantly in either group (P = .2). There was a significant increase in uncorrected visual acuity (UCVA) of 6/6 in each group. In the recutting group, UCVA of 6/6 increased from 3.8% to 65.2% at 6 months, and in the lifting group from 3.6% to 71.1% at 6 months. In the recutting group, seven free flaps and three macerated flaps that required removal occurred. One eye in the recutting group and two in the lifting group developed significant epithelial ingrowth. No patient lost more than one line of best spectacle-corrected visual acuity (BSCVA). CONCLUSION Both procedures were safe, effective, and highly predictable for enhancements, but flap complications may be more likely with recutting.

Central Focal Interface Opacity After Laser in situ Keratomileusis

BACKGROUND The acute onset of a focal central interface opacity with visual loss following LASIK has not been described in the peer reviewed literature. Non-peer reviewed reports of various inflammatory lesions have been recorded. METHODS We describe three cases in which an acute focal stromal interface opacification was identified within 1 week of laser in situ keratomileusis (LASIK). Each case was performed by a different surgeon on a different day, but using the same method, materials, and the Summit Apex Plus excimer laser. Immediately after surgery, all eyes were normal with good unaided vision. The appearance of the central stromal opacity was associated with acute visual deterioration. Preoperative and postoperative cycloplegic refractions, videokeratography, and postoperative slit-lamp biomicroscopy were performed. Each case was treated with intensive topical corticosteroids. RESULTS Each case demonstrated a central circular opacity in the interface between corneal flap and stromal bed, with associated variable stromal thinning. Resolution of the pathological process followed 2 to 4 weeks of treatment with topical corticosteroids and subsequent improvement in slit-lamp biomicroscopy, corneal topography, and vision. Etiology was uncertain. CONCLUSION Central interface opacification is a rare but visually important inflammatory complication of LASIK.