Caitriona Kirwan

Corneal hysteresis using the Reichert ocular response analyser: findings pre- and post-LASIK and LASEK.

Purpose:  To evaluate and compare corneal hysteresis in patients prior to and following laser in situ keratomileusis (LASIK) and laser‐assisted subepithelial keratectomy (LASEK) using the Reichert ocular response analyser (ORA).

Corneal hysteresis and corneal resistance factor in keratoectasia: findings using the Reichert ocular response analyzer.

Aim: To examine corneal hysteresis (CH) and corneal resistance factor (CRF) in normal and ectatic corneas. Methods: CH and CRF were measured using the Reichert Ocular Response Analyzer in patients with clinically diagnosed keratoconus (KC), forme fruste KC (FFKC) and normal eyes. Results: 21 eyes (13 patients) with clinically diagnosed KC and 30 eyes (18 patients) with FFKC were included in the study. Mean CH and CRF in FFKC did not differ from that in pachymetry-matched normal eyes. KC eyes had significantly lower CH and CRF than normal and FFKC eyes. Conclusion: A significant overlap in CH and CRF values among the 3 groups was evident. Our findings do not indicate a role for CH and CRF measurement as a single test to aid in the detection of early ectasia. It may be of use when used in conjunction with other parameters such as aberrometry. CH and CRF values may prove to be useful in monitoring ectasia progression.

Comparative study of higher-order aberrations after conventional laser in situ keratomileusis and laser epithelial keratomileusis for myopia using the technolas 217z laser platform.

PURPOSE To examine changes in higher-order aberrations (HOAs) after PlanoScan laser in situ keratomileusis and (LASIK) and laser epithelial keratomileusis (LASEK). DESIGN Prospective, comparative study. METHODS Myopic patients undergoing LASIK (65 eyes of 36 patients) and LASEK (50 eyes of 28 patients) at a private practice were selected randomly. Surgery was performed using the Technolas 217z laser (Bausch & Lomb, Surrey, United Kingdom). Main outcome measures included uncorrected visual acuity (UCVA), manifest refractive spherical equivalent (MRSE), and aberrometry (Zywave; Bausch & Lomb, Rochester, New York, USA) and were recorded before surgery and at three and 12 months after surgery. RESULTS There was no statistical difference between both groups in terms of MRSE (P = .91), ablation depth (P = .47), scotopic pupil size (P = .38), or optical zone (P = .07). Before surgery, there was no statistical difference in root mean square (RMS) of total (P = .70), third- (P = .79), fourth- (P = .23), and fifth- (P = .33) order aberrations and individual terms. Three months after surgery, RMS of total HOA was raised significantly more (P = .03) after LASIK (1.46-factor increase) than LASEK (1.25-factor increase). One year after surgery, a reduction in total HOAs was observed in 13.8% of LASIK- and 48.5% of LASEK-treated eyes compared with preoperative levels. CONCLUSIONS Postoperative increases in total HOA and vertical coma were significantly greater in LASIK- than in LASEK-treated eyes. Postoperative reduction in total HOAs was observed in a number of eyes with high preoperative levels and occurred more frequently in LASEK-treated eyes.

Laser epithelial keratomileusis in 2010 - a review.

Photorefractive keratectomy, laser epithelial keratomileusis (LASEK) and Epi‐LASIK are all variants of a similar type refractive surgery involving laser on the surface of the cornea and differ mainly in management of the epithelium. Although laser in situ keratomileusis (LASIK) is currently the most popular form of refractive surgery, LASEK is the procedure of choice in some patients. We highlight potential complications of LASEK and how these may be managed. Following laser refractive surgery, corneal thickness is reduced, which has implications for intraocular pressure measurement and glaucoma screening and management. This is particularly important following surface laser procedures where no evidence of previous surgery may be visible. In the event that cataract surgery is required at a later date, correct calculation of the appropriate intraocular lens power can be difficult and it thus important that patients are given their preoperative keratometry readings and refraction. Compared with LASIK patients, those who undergo LASEK are considered to be at lower risk of corneal ectasia. Improved understanding of wound healing post LASEK and better postoperative pain management are ongoing challenges.Photorefractive keratectomy, laser epithelial keratomileusis (LASEK) and Epi-LASIK are all variants of a similar type refractive surgery involving laser on the surface of the cornea and differ mainly in management of the epithelium. Although laser in situ keratomileusis (LASIK) is currently the most popular form of refractive surgery, LASEK is the procedure of choice in some patients. We highlight potential complications of LASEK and how these may be managed. Following laser refractive surgery, corneal thickness is reduced, which has implications for intraocular pressure measurement and glaucoma screening and management. This is particularly important following surface laser procedures where no evidence of previous surgery may be visible. In the event that cataract surgery is required at a later date, correct calculation of the appropriate intraocular lens power can be difficult and it thus important that patients are given their preoperative keratometry readings and refraction. Compared with LASIK patients, those who undergo LASEK are considered to be at lower risk of corneal ectasia. Improved understanding of wound healing post LASEK and better postoperative pain management are ongoing challenges.

Ahmed valve drainage implant surgery in the management of paediatric aphakic glaucoma

Background: Paediatric aphakic glaucoma presents months or years after cataract surgery in children and is a major long term complication. The results of surgical treatment are poor and many children require multiple and repeat procedures with poor visual outcomes. Methods: 13 children (19 eyes) had Ahmed valve implantation surgery, nine of the children had previous procedures such as cycloablation or trabeculectomy. Mitomycin was used at surgery in some patients and valve needling with Healon GV and 5-fluorouracil in some blebs after surgery. SF6 gas was also used at the time of surgery in most children to reform the anterior chamber. Results: 12 of the children (18 eyes) achieved intraocular pressure control of 15 mm Hg or less with a valve alone or with additional medical therapy. Conclusion: Ahmed valve implantation surgery alone or in combination with medical therapy is successful and safe in the management of paediatric aphakic glaucoma.

SCREENING FOR RETINOPATHY OF PREMATURITY

The CRYO-ROP study confirmed the success of treatment for ROP and made screening mandatory. National based screening has been influenced by the varied incidence of disease in developed and developing countries. Most ophthalmologists in developed countries screen infants born between 1000 and 1500 g and between 28 and 31 weeks gestation post menstrual age. The 1984 classification has been updated to highlight the importance of plus disease. The ETROP study findings have resulted in earlier treatment and elevated the importance of screening. Measures such as nesting may help to reduce infant distress during examination. It is important for neonatal units to have an agreed policy on screening and both neonatologist and neonatal nurses have an invaluable role. Diagnostic retinal imaging and telemedicine may have an increasing role in future screening. Timely and accurate screening is the most important first step as earlier treatment results in improved visual prognosis.

5-Year Prospective Follow-Up of Artisan Phakic Intraocular Lenses for the Correction of Myopia, Hyperopia and Astigmatism

Aim: To determine the efficacy and safety of Artisan phakic intraocular lenses (IOLs) for refractive error correction. Methods: A prospective study was conducted on patients undergoing Artisan phakic IOL implantation for myopia, hyperopia or astigmatism from 2002 to 2008. Visual acuity, manifest refractive spherical equivalent (MRSE), endothelial cell counts and higher order aberrations were recorded pre- and postoperatively. Results: One hundred and fifty-one (84 patients) myopic (mean MRSE –11.2 ± 4.1 D) and 14 (7 patients) hyperopic eyes (mean MRSE 7.1 ± 1.3 D) were treated. Twenty eyes (11 patients) had toric IOLs to correct astigmatism (mean MRSE –9.05 ± 6.13 D, mean astigmatism 4.06 ± 1.26 D). Three months postoperatively, mean MRSE in 37.6% of eyes was within ±0.5 D, 61.8% within ±1.0 D and 91.4% within ±2.0 D. 18.5% underwent keratorefractive surgery to correct residual refractive error. A 1.56-fold increase occurred in 4th order spherical aberration. Endothelial cell loss was 1.45% at 1 year and negligible at 5 years. Fifty-four eyes (29.2%) gained one or more lines of best corrected visual acuity and no eye lost a line. Conclusion: Artisan phakic IOLs are safe and effective for refractive error correction.

Prospective contralateral eye study to compare conventional and wavefront‐guided laser in situ keratomileusis

Purpose:  To compare outcomes of customized/wavefront guided with conventional ablation in myopic patients with or without astigmatism undergoing laser in situ keratomileusis.

Refractive surgery in patients with accommodative and non-accommodative strabismus: 1-year prospective follow-up

Aim To determine the efficacy and safety of keratorefractive surgery in patients with accommodative and non-accommodative strabismus in a prospective study. Methods Preoperative assessment included uncorrected (UCVA) and best-corrected visual acuity (BCVA), manifest and cycloplegic refraction and orthoptic examination. Laser in situ keratomileusis, laser epithelial keratomileusis and Artisan phakic intraocular lens implantation were performed. All treated eyes had a BCVA of at least 6/18 preoperatively. One year postoperatively, visual acuity, refractive error and ocular alignment were reassessed. Results 28 patients (nine male, 19 female) of mean age 33.0±10.0 years (range 20–59) were included in the study. Esotropia was present in 16 patients; nine fully accommodative, three partially accommodative and four non-accommodative. Twelve patients had exodeviations; 10 exotropia and two exophoria and a history of strabismus surgery. Excellent visual and refractive outcomes were obtained postoperatively. There was no loss, and one eye gained a line of BCVA. Fully accommodative esotropes attained orthophoria or microtropia. Improved ocular alignment occurred in partially accommodative esotropes and myopic exotropes. No patient experienced decompensation of strabismus or diplopia. Conclusions Refractive surgery may be performed successfully in patients with accommodative and non-accommodative strabismus. However, great care must be taken when determining patient suitability. This is of particular importance in young hyperopic patients to prevent decompensation of ocular alignment over time.

Higher Order Aberrations in Children With Amblyopia

PURPOSE To quantify and characterize higher order aberrations in eyes of children with amblyopia. METHODS Higher order aberrations were measured in a group of children using the iTrace Visual Function Analyzer (Tracey Technologies, Houston, TX). Children involved in the study had unilateral amblyopia secondary to strabismus or anisometropia. RESULTS Thirty children between 6 and 17 years old (mean: 10.7 years) were studied. Fifteen children had strabismic and 15 had anisometropic amblyopia. No statistically significant difference was found in mean root mean square values of total higher order aberrations, coma, spherical, higher order astigmatism, trefoil, or 3rd, 4th, 5th, or 6th order terms of normal and amblyopic eyes. CONCLUSION Higher order aberrations are similar in amblyopic eyes due to strabismus or anisometropia and normal fellow eyes. Unlike lower order aberrations such as sphere and cylinder, higher order aberrations are unlikely to play a role in the development of amblyopia.