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Biomedical subjects

Prema Padmanabhan

Publications and source records attributed to Prema Padmanabhan.

At least 19 recordsLinked to original sources
PubMed2006

Results of deep lamellar keratoplasty using the big-bubble technique in patients with keratoconus.

PURPOSE: To evaluate the efficacy of deep lamellar keratoplasty using the big-bubble technique in patients with keratoconus. DESIGN: Interventional case series. METHODS: Thirteen eyes of 12 patients (eight male and four female subjects) with moderate to advanced keratoconus and intolerance to contact lens wear were included in this study. Deep lamellar keratoplasty was performed by the intrastromal air injection technique. Full-thickness donor tissue devoid of Descemet membrane and endothelium was then sutured into place. Best-corrected visual acuity, refractive results, surgical technique, and complication rates were analyzed. RESULTS: Big bubble was successfully achieved in nine eyes (69.2%). Average postoperative best-corrected visual acuity was 20/25 (range 20/50 to 20/20) at a mean follow-up of 5 months. Intraoperative microperforation of Descemet membrane occurred in two eyes (15.3%). Three eyes (23%) developed a steroid-induced increase in intraocular pressure, which responded to medical therapy. CONCLUSIONS: Deep lamellar keratoplasty that uses the big-bubble technique is safe and effective in patients with keratoconus. Visual outcome is comparable to standard penetrating keratoplasty, without the risk of endothelial rejection.

Adolescent↗
PubMed2006

Initial results of small incision deep lamellar endothelial keratoplasty (DLEK).

PURPOSE: To evaluate the results of replacing the posterior stroma and endothelium, using small incision deep lamellar endothelial keratoplasty (DLEK) surgical technique, in patients with corneal endothelial dysfunction. DESIGN: Noncomparative case series. METHODS: Fifteen eyes of 15 patients (six males and nine females) with endothelial dysfunction were included in this study. Through a 5-mm scleral incision, a deep lamellar pocket was created across the cornea, followed by excision of an 8.0-mm disk of posterior lamellar corneal tissue. Same size lamellar donor disk was prepared and placed in position without the need of suture fixation. Best spectacle-corrected visual acuity (BSCVA), refraction, endothelial cell density, corneal topography, and corneal thickness were analyzed. RESULTS: Average BSCVA preoperative was 20/200 (range 20/40 to hand movements (HM)), improving to 20/50 (range 20/20 to 20/120) at a mean follow-up of 7.2 months. Average refractive astigmatism at last follow-up was 1.46+/-1.21 diopters (range, 0 to 4 diopters). Preoperative average donor endothelial cell density was 2047+/-311 cells/mm2, and that at last follow-up was 1732+/-514 cells/mm2. Preoperative average pachymetry was 801.4+/-211.3 microm, improving to 553+/-90.4 microm at last follow-up. CONCLUSIONS: Initial results with small incision DLEK procedure indicate that it is a safe procedure that provides healthy donor endothelial cell count and function postoperatively, with encouraging visual results.

Adult↗
PubMed2006

Monochromatic aberrations in eyes with different intraocular lens optic designs.

PURPOSE: To study the wavefront aberration profile of eyes with three different types of intraocular lenses (IOLs)--the Tecnis Z9000 (modified prolate surface design) (Pfizer, New York, NY), the Acrysof MA60BM (unequal biconvex optic) (Alcon, Ft Worth, Tex), and the Sensar Optiedge AR40e (equibiconvex optic) (AMO, Santa Ana, Calif)--in eyes following cataract surgery. METHODS: This study was conducted in two parts. The first part was a randomized open study of 32 eyes of 16 patients who underwent bilateral phacoemulsification with a foldable IOL in the capsular bag. A Tecnis Z9000 IOL was implanted in one eye and an Acrysof MA60BM IOL in the fellow eye. The ALLEGRETTO WAVE Analyzer (Wavelight Laser Technologies AG, Erlangen, Germany) was used to measure ocular aberrations 2 weeks after surgery. A paired t test was used to compare each Zernike term from Z3(-3) to Z6(6) between fellow eyes (pupil diameter = 6 mm). In the second part of the study, the wavefront aberrations of 16 eyes that underwent an identical surgical procedure as in the first part of the study but had a Sensar Optiedge AR40e IOL implanted were studied and compared with eyes with the Tecnis Z9000 and Acrysof MA60BM IOLs. RESULTS: The mean spherical aberration (Z4(0)) was statistically significantly lower in eyes with a Tecnis Z9000 IOL (Z4(0) = 0.07 +/- 0.12 microm) compared with eyes with an Acrysof MA60BM IOL (Z4(0) = 0.29 +/- 0.20 microm, P < .001) and with eyes with a Sensar Optiedge AR40e IOL (Z4(0) = 0.20 +/- 0.09 microm, P = .002). No statistically significant differences were noted in any of the Zernike terms between eyes with Acrysof MA60BM and Sensar Optiedge AR40e IOLs, or in the root-mean-square (RMS) of total higher order aberrations among the three IOL groups. CONCLUSIONS: The implantation of a Tecnis Z9000 IOL produces a significant reduction in spherical aberration of the eye. No significant differences were noted in the wavefront profile between eyes with Acrysof MA60BM and Sensar Optiedge AR40e IOLs. No significant differences were found in the RMS of total higher order aberrations among the three IOL groups.

Adult↗
PubMed2006

Wavefront aberrations in eyes with Acrysof monofocal intraocular lenses.

PURPOSE: To characterize and measure the ocular aberrations in eyes implanted with monofocal intraocular lenses (IOLs) and to study any correlation between postoperative aberrations and surgical factors. METHODS: A Tscherning aberroscope was used to measure the wavefront aberrations of 62 eyes that had undergone phacoemulsification with the implantation of foldable monofocal Acrysof MA60BM IOLs (Alcon Laboratories Inc, Ft Worth, Tex). The Zernike coefficients, measured with a pupil diameter of 6 mm, were compared with those of a normal dataset of 82 eyes of healthy young myopes. RESULTS: Spherical aberration (Z(0)4) was the most predominant higher order aberration, with a mean value of 0.37 +/- 0.16 microm. A statistically significant linear relationship was noted between the magnitude of postoperative spherical aberration and the dioptric power of the IOL. The mean spherical aberration was 33 times more in the pseudophakic group than in normal young myopic eyes. The other major higher order aberrations were trefoil (Z(-3)3) with a mean of -0.13 +/- 0.22 microm and vertical coma (Z(-1)3) with a mean value of -0.11 +/- 0.23 microm. On average, the root-mean-square of higher order aberrations in pseudophakic eyes was 2.1 times that in a normal population of young myopic eyes. CONCLUSIONS: Eyes that undergo cataract surgery with monofocal IOL implantation suffer from significant higher order aberrations. The optical design of the IOL is most likely responsible for the increase in spherical aberration, the magnitude of which is a function of the dioptric power of the IOL.

Acrylic Resins↗
PubMed2005

Deep anterior lamellar keratoplasty combined with autologous limbal stem cell transplantation in unilateral severe chemical injury.

PURPOSE: To evaluate the efficacy of deep anterior lamellar keratoplasty combined with autologous limbal stem cell transplantation for ocular surface reconstruction and visual rehabilitation in eyes with unilateral, late-stage, severe chemical injury. METHODS: This was a retrospective, noncomparative, interventional case series that included 7 eyes of 7 patients, with severe unilateral late stage chemical injury, exhibiting corneal vascularization, conjunctivalization, and extensive corneal scarring were treated at the C. J. Shah Cornea Service, Sankara Nethralaya, a tertiary care center. Surgical procedures included releasing symblepharon adhesions, excising epibulbar fibrous tissue, superficial keratectomy to remove fibrovascular tissues over cornea, deep anterior lamellar dissection, grafting a lamellar corneal button, and transplanting autologous limbal graft, with or without amniotic membrane transplantation. The main outcome measures were relief of patient symptoms, postoperative recovery of the ocular surface, corneal clarity, corneal epithelial stability, and best corrected visual acuity. RESULTS: The mean duration between the injury and surgery was 24.4 +/- 21.8 months. No intraoperative complications were noted. Successful epithelialization was achieved in all eyes. The reconstructed corneal surface remained stable during the entire follow-up period (mean follow-up, 16.57 +/- 5.12 months). All patients had resolution of ocular symptoms. Remarkable improvement in vision was noted in all (85.7%) except 1 eye in which recovery was limited due to amblyopia. The average best corrected visual acuity at last follow-up was 20/50. No complications were noted in the donor fellow eye. CONCLUSIONS: DALK combined with autologous limbal transplantation can restore a healthy, stable ocular surface, besides providing a clear cornea that remarkably improves the visual acuity, in patients with unilateral, late stage, severe chemical injury.

Adolescent↗
PubMed2005

Bilateral epithelial defects after laser in situ keratomileusis. Clinical features, management and outcome.

PURPOSE: To describe the preoperative characteristics, intraoperative details, management, and postoperative in patients with bilateral epithelial defects after laser in situ keratomileusis (LASIK). METHODS: Retrospective non-comparative case series. RESULTS: Six patients with bilateral epithelial defects after LASIK were part of a cohort of 605 patients undergoing bilateral LASIK at our center from December 2001 to April 2003. The mean age of the patients (5M:1F) was 28.5 +/- 7.9 years, and the average pretreatment myopic spherical equivalent (SE) refraction was 7.3 +/- 0.7 D (-4, -12.25D). An epithelial flap was present in 6 eyes and an epithelial defect with a mean diameter of 3 mm (2mm, 6mm) was seen in 6 eyes. In four patients the epithelial disturbance was bilaterally similar. All defects occurred in the inferior cornea and the epithelial flaps had the hinge positioned superiorly. None of the patients had ocular or systemic risk factors that could have resulted in this complication. A bandage contact lens was used in 6 eyes. At last follow-up of 5.5 +/- 9.5 months (0.25, 21 months), unaided visual acuity was 6/9 or better in 10 eyes. Best spectacle-corrected visual acuity (BSCVA) was maintained in 8 eyes, while 4 eyes lost one line of BSCVA. Recurrent corneal erosions were not reported in the follow-up period. CONCLUSIONS: These patients represent a hitherto unrecognised group of individuals who appear to have a subclinical weakness of adhesion of the corneal epithelium to the underlying structures, which is not evident on clinical examination. This results in bilateral epithelial disturbances after LASIK. Appropriate management results in satisfactory clinical outcomes. Other options for treatment of the fellow eye of such patients include the use of a different microkeratome, release of suction during the reverse pass of the Hansatome microkeratome, and photorefractive keratectomy if the refractive error is low.

Adult↗
PubMed2005

Chronic microsporidial stromal keratitis in an immunocompetent, non-contact lens wearer.

An 82-year-old healthy man with unilateral chronic stromal keratitis, initially diagnosed to have viral keratitis and refractory to medical therapy, showed numerous oval, microsporidial organisms, measuring 4-5 m in length in the corneal biopsy. Penetrating keratoplasty, followed by treatment with systemic albendazole and topical propamidine isethionate resulted in resolution of the infection. Electron microscopy of the keratoplasty specimen demonstrated sporoblasts with diplokaryotic nuclei and multiple coils of the filament. The light and electron microscopic features were consistent with microsporidial keratitis.

Aged↗
PubMed2004

Interrupted sutures at the hinge site to manage a free flap during laser in situ keratomileusis.

Two patients developed free flaps intraoperatively during laser in situ keratomileusis. After excimer laser treatment was performed, the free flap was replaced, maintaining proper alignment. Interrupted sutures were placed superiorly at the intended hinge site to secure the free flap. The uncorrected visual acuity was 20/30 in the affected eyes of both patients after treatment. At the 6-month follow-up, there were no flap-related complications and there was no loss of best corrected visual acuity.

Adult↗
PubMed2004

Photorefractive keratectomy versus laser in situ keratomileusis to prevent keratectasia after corneal ablation.

A 27-year-old man had excimer photoastigmatic keratectomy in the right eye and laser in situ keratomileusis in the left eye for the treatment of equivalent myopia. Preoperative slitlamp examination did not reveal evidence of keratoconus, central corneal pachymetry was 485 microm in the right eye and 500 microm in the left eye, and corneal topography revealed asymmetric bow-tie astigmatism with inferior steepening in the right eye and a small area of inferior steepening in the left eye. Twenty-two months after surgery, the patient complained of poor vision in the left eye. Slitlamp examination of the left eye revealed central corneal thinning and protrusion, with a Fleischer ring within the flap. Corneal topographic evaluation revealed a stable map in the right eye and central corneal steepening indicative of keratectasia in the left eye.

Adult↗
PubMed2003

Keratectasia in 2 cases with pellucid marginal corneal degeneration after laser in situ keratomileusis.

We report 2 patients who experienced progressive blurring of vision following myopic laser in situ keratomileusis (LASIK) in 1 eye (Case 1) and bilaterally (Case 2). High against-the-rule astigmatism, associated with perilimbal thinning inferiorly, was seen on refraction in all eyes. Regional corneal pachymetry confirmed the peripheral corneal thinning inferiorly. Corneal topography revealed the typical features of pellucid marginal corneal degeneration (PMCD) in the untreated eye of Case 1. Advanced changes were noted in the fellow eye. The corneal topography findings in Case 2 were similar to those seen in PMCD. Patients with early PMCD may present to the refractive surgeon with a stable refraction, normal corrected visual acuity, and adequate central corneal thickness. Corneal topography data along with regional corneal pachymetry must be interpreted carefully to detect these cases. Laser in situ keratomileusis can lead to a rapid progression of PMCD.

Adult↗
PubMed2002

Bilateral macular hemorrhage caused by azathioprine-induced aplastic anemia in a corneal graft recipient.

PURPOSE: To report the occurrence of bilateral macular hemorrhage following the use of azathioprine for immunosuppression in a corneal transplant recipient. METHODS: The patient underwent therapeutic penetrating keratoplasty for progressive fungal keratitis in his left eye. Although the infection did not recur, the graft failed with vascularization of the cornea in three quadrants. He underwent repeat penetrating keratoplasty 2 years later and was treated with azathioprine (100 mg daily) to enhance graft survival. Four months after instituting azathioprine therapy, he developed aplastic anemia and macular hemorrhage in both eyes. RESULTS: Fluorescein angiography revealed a preretinal location of the macular hemorrhage. After cessation of azathioprine therapy and treatment with blood component replacement, hematological parameters improved and the macular hemorrhage cleared with good visual recovery during the next 2 months. CONCLUSION: This report highlights the serious ocular and systemic complications that can occur following the use of systemic immunosuppressants after ophthalmic surgery.

Adult↗