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Biomedical subjects

A Brahma

Publications and source records attributed to A Brahma.

13 recordsLinked to original sources
PubMed2001

Safety and predictability of laser in situ keratomileusis enhancement by flap reelevation in high myopia.

PURPOSE: To evaluate the safety and predictability of laser in situ keratomileusis (LASIK) retreatment following primary procedures for high myopia and astigmatism. SETTING: Corneal Diseases and Excimer Laser Research Unit, Department of Ophthalmology, University of Dundee, Dundee, United Kingdom. METHODS: This prospective observational study of retreatment comprised a cohort of 109 eyes having primary LASIK for high myopia and astigmatism with a spherical equivalent (SE) of -9.70 diopters (D) +/- 4.06 (SD). Twenty-four eyes (22%) with an initial myopic SE of -9.83 +/- 3.50 D, a comparable subset of the entire group (P < .05), had retreatment for residual myopia (-3.02 +/- 2.17 D) to improve uncorrected visual acuity (UCVA) by reelevating the corneal flap and ablating the stromal bed. RESULTS: The mean follow-up after retreatment was 12.8 +/- 5.1 months (range 1.5 to 24 months; 19 eyes >/=6 months, 13 eyes > or = 12 months). The mean myopic SE was reduced to +0.53 +/- 0.62 D at 1 week, +0.05 +/- 0.50 D at 1 month, +0.30 +/- 0.50 D at 6 months, and +0.18 +/- 0.42 D at the latest follow-up, 12.8 months. At the latest review, 62% of eyes were within +/-0.50 D of emmetropia and 100% were within +/-1.00 D. The mean refraction did not alter statistically between 1 week and subsequent times. The mean UCVA improved from 6/30 prior to retreatment to 6/9 at the latest follow-up. Uncorrected visual acuity of 6/6 or better, 6/9 or better, and 6/12 or better was achieved by 33.0%, 75.0%, and 95.8% of eyes, respectively. No significant complications that led to a loss of best corrected visual acuity were encountered, although retreatment procedures were more uncomfortable than primary procedures and self-limiting; epithelial ingrowth that did not threaten vision was common, and 2 patients complained of nighttime visual symptoms. CONCLUSIONS: Retreatment of residual myopia by reelevating the flap was relatively safe and predictable, with a low risk of sight-threatening complications. However, longer term studies may be required to detect late complications.

Adult↗
PubMed2001

Comparison of corneal thickness measurements using ultrasound and Orbscan slit-scanning topography in normal and post-LASIK eyes.

PURPOSE: To compare corneal thickness measurements made by ultrasonic and slit-scanning techniques in normal eyes and in eyes after laser in situ keratomileusis (LASIK). SETTING: Corneal Diseases and Excimer Laser Research Unit, University of Dundee, Dundee, Scotland. METHODS: Central corneal thickness (CCT) was measured in 101 eyes of 59 normal subjects and in 30 eyes of 21 post-LASIK patients. Measurements were made with an Orbscan slit-scanning elevation topographer and immediately afterward with an ultrasound pachymeter. RESULTS: The difference in mean CCT between ultrasound (538.0 microm +/- 36.7 [SD]) and Orbscan (566.6 +/- 40.7 microm) pachymetry was statistically significant (P <.001) in the normal eyes; the Orbscan measurement was approximately 28 microm higher than that of the ultrasound pachymeter. The difference in mean CCT between the ultrasound and the slit-scanning techniques was also statistically significant in the post-LASIK eyes (mean values 475.3 +/- 50.3 microm and 461.9 +/- 74.2 microm, respectively; P <.0001). Differences in CCT in individual subjects were much more variable in the post-LASIK eyes than in the normal eyes. The Bland and Altman method for assessing clinical agreement between 2 instruments showed that in 95% of cases, the CCT measurements with both instruments would be within 65 microm in normal eyes and 150 microm in post-LASIK eyes. CONCLUSION: Central corneal thickness measurements were, on average, 28 microm higher with the Orbscan than with the ultrasound pachymeter in normal eyes and 13 microm lower in post-LASIK eyes. The degree of variability within each group indicated that these 2 techniques are not clinically comparable, precluding interchangeable use of their data in planning or assessing corneal surgery.

Adult↗
PubMed2000

Management of pellucid marginal corneal degeneration.

PURPOSE: A retrospective study to ascertain the management of pellucid marginal corneal degeneration (PMCD). METHOD AND RESULTS: Sixteen patients (average age 42.6 years) presented with PMCD. PMCD was bilateral in 13 and unilateral in 3 patients. Eight eyes underwent surgery. Nineteen eyes were managed non-surgically. Surgery involved corneal wedge excision (WE) (6 eyes), penetrating keratoplasty (PK) (3 eyes) and lamellar thermo-keratoplasty (LTK) (1 eye). Immediate pre-operative average visual acuity (VA) was 6/24, 6/10 and 6/60 with an average pre-operative astigmatism of 11.40 D, 9.75 D and 20.5 D for WE, PK and LTK respectively. After an average post-operative follow-up of 57 months, 66 months and 1 year, the average astigmatism was 8.90 D, 4.63 D and 6.00 D with an average final VA of 6/19, 6/15 and 6/6 for WE, PK and LTK respectively. In the nonsurgical group, at presentation, 40% of eyes had a VA of 6/12 or better. After an average follow-up period of 32.3 months, 80% of eyes had a visual acuity of 6/12 or better. Optical correction was achieved with spectacles and or contact lenses. CONCLUSIONS: Surgical correction for PMCD provides poor long-term reduction of astigmatism. Patients with PMCD may be adequately corrected in the long term by the use of scleral fitted gas-permeable contact lenses.

Adult↗
PubMed2000

Severe sclerokeratitis due to Pseudomonas aeruginosa in noncontact-lens wearers.

PURPOSE: To review the clinical presentation, treatment and outcome in four cases of severe anterior segment infection by Pseudomonas aeruginosa unrelated to contact lens wear. METHODS: Four cases presenting over an 18 month period were reviewed. RESULTS: The cases had variable presenting features and outcomes. Complications such as persistent infection, corneal thinning and phthisis bulbi were noted. Possible factors influencing adherence and tissue disruption are discussed. CONCLUSIONS: Suspicion of infection by P. aeruginosa and prompt isolation of the organism is needed early in the course of disease. Intensive and prolonged treatment with parenteral and topical antibiotics combined with judicious use of topical steroid gives the best chance of a favourable outcome.

Aged↗
PubMed2000

Centration of donor trephination in human corneal transplantation.

PURPOSE: To develop and evaluate a new method to quantify centration of the trephined donor cornea relative to the limbus. METHODS: After human donor corneas were trephined for penetrating keratoplasty, the remaining corneoscleral discs were stained and subjected to image analysis. The centration of the excised donor cornea relative to the limbus was calculated by measuring their centroids from the "captured" images. RESULTS: Fifty-two corneoscleral discs were analyzed. The average deviation from the centre was 0.32 mm (SD, 0.18 mm). Neither surgeon nor the type of trephine significantly influenced the mean centroid deviation. CONCLUSION: We have developed and evaluated a method to quantify centration of human donor cornea. In a small series, decentration did not correlate significantly with either the surgeon or the trephine.

Cornea↗
PubMed2000

Visual function after penetrating keratoplasty for keratoconus: a prospective longitudinal evaluation.

AIMS: To evaluate visual function and vision specific health status in patients undergoing penetrating keratoplasty for keratoconus. METHODS: A prospective longitudinal study measuring logMAR visual acuity, contrast sensitivity, disability glare, binocular visual field, stereoacuity, and subjective visual function (VF-14) was conducted on 18 patients with keratoconus undergoing penetrating keratoplasty (PK), including six patients who had already had PK in the fellow eye. Data were collected preoperatively and at 3, 9, and 18 months after surgery. RESULTS: Within 3 months of surgery there was significant improvement in aided visual acuity, contrast sensitivity, and stereoacuity (p<0.05); disability glare (p<0.05) no longer had a significant detrimental effect on these variables. VF-14 score improved significantly throughout the postoperative period (p<0.05). There was significant correlation of the VF-14 score with aided visual acuity, binocular visual field, and stereoacuity. Postoperative astigmatism (<4D v >4D) did not affect the VF-14 score significantly. CONCLUSIONS: There is substantial and rapid improvement in visual function and vision specific health status in keratoconic patients as a result of uncomplicated penetrating keratoplasty.

Adult↗
PubMed1999

Lateral canthotomy and inferior cantholysis: an effective method of urgent orbital decompression for sight threatening acute retrobulbar haemorrhage.

Retrobulbar haemorrhage (RBH) occurs in a variety of situations. It can complicate facial fractures, orbital surgery and retrobulbar injections and can occur spontaneously. It is relatively uncommon and sight-threatening RBH is even less common. If not detected early enough it can lead to devastating loss of vision. We have collected five cases of acute RBH, following trauma, associated with a profound reduction in vision. In each case a permanent loss of vision was avoided using a lateral canthotomy and inferior cantholysis approach to obtain urgent orbital decompression.

Acute Disease↗