Biomedical subjects

Ian F Comaish

Publications and source records attributed to Ian F Comaish.

5 recordsLinked to original sources

PubMed2003

Conductive keratoplasty to correct residual hyperopia after corneal surgery.

Conductive keratoplasty (CK) is an electrical-current-based technique for steepening the central cornea to reduce low to moderate hyperopia. We report 4 patients who had CK to correct hyperopia after laser in situ keratomileusis (LASIK) and were followed for at least 6 months. An overcorrection was noted after the CK procedure in all patients, but no sight-threatening complications arose. Conductive keratoplasty appears to be safe and well tolerated after LASIK. However, the algorithms should be modified to increase the predictability of the CK procedure in previously treated eyes.

Cornea↗

PubMed2002

Laser in situ keratomileusis for residual myopia after photorefractive keratectomy.

PURPOSE: To evaluate the efficacy and safety of laser in situ keratomileusis (LASIK) for myopic regression and undercorrection after photorefractive keratectomy (PRK). SETTING: The Eye Institute, Sydney, Australia. METHODS: Fifty eyes of 32 patients were treated by LASIK for residual myopia following primary PRK. The mean spherical equivalent refraction (SEQ) was -2.92 diopters (D) +/- 1.57 (SD) (range -0.75 to -7.88 D). The mean refractive cylinder was 0.96 +/- 0.74 D (range 0 to 3.50 D). For analysis, the eyes were divided into 2 groups: those with 0 or low corneal haze (Group 1) and those with severe corneal haze (Group 2). In Group 1, the SEQ was -1.99 +/- 0.79 D (range -0.75 to -3.75 D) and in Group 2, -3.77 +/- 1.62 D (range -0.75 to -7.90 D). The procedure was performed using the Chiron Automated Corneal Shaper and the Summit Apex Plus laser. The mean interval between PRK and LASIK was 25 months (range 9 to 59 months). The following parameters were studied before and after LASIK retreatment: SEQ, mean refractive cylinder, uncorrected visual acuity (UCVA), and best corrected visual acuity (BCVA). Complications after LASIK retreatment were evaluated. RESULTS: Six months after LASIK, the mean SEQ in all eyes was -0.65 +/- 0.86 D (range +1.50 to -3.35 D); 70.0% of eyes were within +/-1.00 D of emmetropia and the UCVA was 6/12 or better in 72.5%. The mean SEQ in Group 1 was -0.22 +/- 0.55 D (range -0.88 to -1.50 D) and in Group 2, -0.97+/- 0.92 D (range 0.12 to -3.25 D); the UCVA was 6/12 or better in 94.0% of eyes in Group 1 and in 56.0% in Group 2. No statistically significant between-group difference was found in lines of Snellen acuity lost or gained at 6 months. No eye lost more than 1 line of BCVA. CONCLUSIONS: Laser in situ keratomileusis appears to be a safe, effective, and predictable procedure for treating eyes with 0 or low haze with residual myopia after PRK. It is less predictable in eyes with severe haze.

Adult↗

PubMed2002

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

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.

Biomechanical Phenomena↗

PubMed2002

Patients treated with vigabatrin exhibit central visual function loss.

PURPOSE: To investigate visual function in the central 10 degrees in patients who have undergone vigabatrin (VGB) antiepileptic drug (AED) therapy with the aim of identifying a clinical regimen for assessing central visual function. METHODS: The sample comprised 12 epilepsy patients (mean age, 38.6 +/- 11.7 years) who had been treated with VGB (either as monotherapy or polytherapy). A number of central visual-function tests were carried out for each eye, including high-contrast LogMAR visual acuity, short-wavelength automated perimetry (SWAP 10-2), spatial contrast sensitivity (CSV-1000), and Farnsworth-Munsell (FM) 100-hue colour discrimination. RESULTS: The group mean cumulative VGB dose was 5,086 +/- 3,245 g. The average SWAP 10-2 mean deviation (MD) for the group was -3.24 +/- 3.23 dB; 14 eyes of eight patients showed defects (range, -1.62 to -9.46 dB). The square root of the group mean total error score for FM 100-hue was 7.42 +/- 3.84; nine eyes of five patients were classified as abnormal with an unsolved colour axis suggestive of complex drug interactions. For contrast sensitivity, 15 eyes of eight patients yielded abnormal results in one or more spatial frequencies. Defects were more prominent at higher spatial frequencies. Overall, four patients had defects in all three visual-function tests, six patients had mixed defects, and two patients were normal. CONCLUSIONS: Visual-function deficits in epilepsy patients treated with VGB are present in the central 10 degrees of the retina. We recommend a battery of investigations, including SWAP 10-2 and spatial contrast sensitivity testing, to assess central visual function.

Adult↗

PubMed2002

Phakic intraocular lenses.

Since Zaldivar's review of phakic intraocular lenses in these pages in 2000 [1**], further reports of experience with this technology have emerged. Their relative advantages and disadvantages over competing technologies are becoming clearer. Clinical trials, including Food & Drug Administration (FDA) trials, have shown predictability, stability, and efficacy. Safety of these implants over the long term remains a concern, but in some situations, at least, phakic intraocular lenses are becoming the refractive correction of choice. This brief review looks at the most recent data to emerge regarding phakic intraocular lenses.

Anterior Chamber↗