Biomedical subjects

Harkaran S Bains

Publications and source records attributed to Harkaran S Bains.

7 recordsLinked to original sources

PubMed2004

Clinical outcomes using the NAVEX platform.

The NIDEK Advanced Vision Excimer Laser (NAVEX) platform has been used to treat primary eyes and in a wide variety of therapeutic applications. Use of an extremely robust scanning slit skiascopy aberrometer has enabled the treatment of eyes in the latter category. Primary outcomes using NAVEX have shown a reduced induction of higher order aberrations, a maintenance or gain of contrast sensitivity in most patients, and excellent refractive outcomes. By using an ablation profile that minimizes the amount of induced spherical aberrations, large effective optical zones are seen postoperatively.

Cornea↗

PubMedDate not supplied

Comparison of laser in situ keratomileusis outcomes with the Nidek EC-5000 and Meditec Mel 70 excimer lasers.

PURPOSE: To report refractive outcomes of laser in situ keratomileusis (LASIK) for myopia with and without astigmatism using the Nidek EC-5000 and Meditec Mel 70 excimer laser systems. METHODS: A retrospective analysis of refractive outcomes with each laser was conducted. Approximately 5700 eyes treated for myopia and myopic astigmatism were analyzed. Preoperative sphere ranged from -0.25 to -15.50 D and cylinder ranged from -0.75 to -5.50 D. All statistical analyses were performed by Datagraph med version 2.8 refractive analysis software. RESULTS: With the Nidek EC-5000 at 6 months after LASIK, mean spherical equivalent refraction was -0.24 D with 72% of eyes within +/- 0.50 D. In the Meditec cohort, the mean spherical equivalent was -0.54 D with 55% of eyes +/- 0.50 D. CONCLUSION: Eyes treated for myopia and astigmatism with either of these lasers showed early refractive stability and similar efficacy. Higher incidences of epithelial ingrowth and haze were present in the Meditec treated eyes.

Astigmatism↗

PubMedDate not supplied

Nidek OPD-scan analysis of normal, keratoconic, and penetrating keratoplasty eyes.

PURPOSE: To determine by wavefront analysis the difference between eyes considered normal, eyes diagnosed with keratoconus, and eyes that have undergone penetrating keratoplasty METHODS: The Nidek OPD-Scan wavefront aberrometer was used to measure ocular aberrations out to the sixth Zernike order. One hundred and thirty eyes that were free of ocular pathology, 41 eyes diagnosed with keratoconus, and 8 eyes that had undergone penetrating keratoplasty were compared for differences in root mean square value. Three and five millimeter root mean square values of the refractive power aberrometry maps of the three classes of eyes were compared. Radially symmetric and irregular higher order aberration values were compared for differences in magnitude. RESULTS: Root mean square values were lower in eyes free of ocular pathology compared to eyes with keratoconus and eyes that had undergone penetrating keratoplasty. The aberrations were larger with the 5-mm pupil. Coma and spherical aberration values were lower in normal eyes. CONCLUSION: Wavefront aberrometry of normal, pathological, and eyes after surgery may help to explain the visual distortions encountered by patients. The ability to measure highly aberrated eyes allows an objective assessment of the optical consequences of ocular pathology and surgery. The Nidek OPD-Scan can be used in areas other than refractive surgery.

Corneal Topography↗

PubMedDate not supplied

Optimized prolate corneal ablation: case report of the first treated eye.

PURPOSE: To present the first patient treated with an optimized prolate ablation algorithm (OPA) with the NIDEK Advanced Vision Excimer laser platform (NAVEX; NIDEK, Gamagori, Japan). METHODS: A patient with moderate myopia and large scotopic pupils received contralateral LASIK treatment, treating one eye with OPA and the other with conventional treatment. RESULTS: At 3 months postoperatively, corneal topography and wavefront analysis show a prolate result with the OPA treatment and an oblate result with the conventional treatment. CONCLUSIONS: The creation of prolate cornea over the entire scotopic pupil, the reduction of spherical aberrations, and an ablation architecture that compensate for age-related changes was achieved immediately after LASIK. The OPA treatment may result in better visual quality over the long-term compared to conventional LASIK.

Adult↗

PubMedDate not supplied

Five techniques for improving outcomes of hyperopic LASIK.

PURPOSE: To determine whether five changes to our hyperopic LASIK protocol produced better outcomes. METHODS: Five changes, both technical and surgical, were instituted for the treatment of hyperopia. These five changes were nomogram refinements accounting for accommodation, use of a 7.0-mm optical zone and a 9.5-mm transition zone, a targeted mean flap diameter of 10.5 mm, sequential interruption of the laser ablation, and cleaning of the interface. The study comprised 43 eyes undergoing LASIK for hyperopia or hyperopic astigmatism with a mean preoperative spherical equivalent refraction of +2.28 diopters (D), a mean sphere of +1.93 D (range: +4.25 to +0.25 D), and mean cylinder of +1.10 D (range: +4.50 to +0.25 D). The NIDEK CXII excimer laser was used for all treatments. RESULTS: From 1 day to 3 months postoperatively, the mean hyperopic shift was <0.50 D. Postoperatively, the number of patients achieving a distance best spectacle-corrected visual acuity (BSCVA) of 20/20 gradually increased to 93% by 3 months. The number of eyes that achieved 20/15 increased by 11.7% compared to preoperatively. Eighty-eight percent of eyes maintained or gained lines of BSCVA. Four patients lost 1 line of BSCVA. One patient lost >1 line of vision due to visually significant microstriae. CONCLUSIONS: The outcomes support the observation that five surgical and technical modifications to the hyperopic LASIK procedure result in excellent visual quality and refractive outcomes and a low rate of regression.

Adult↗

PubMedDate not supplied

Clinical outcomes of CATz versus OPDCAT.

PURPOSE: To compare refractive outcomes, wavefront outcomes, and corneal asphericity indices (Q values) for patients treated with wavefront-guided or topography-guided custom ablations using the NIDEK Advanced Vision Excimer Laser System (NAVEX). METHODS: A total of 196 eyes of 98 patients underwent wavefront-guided or topography-guided LASIK. A contralateral study of 28 eyes of 14 patients who underwent customized aspheric treatment zone (CATz) ablation in one eye and optical path difference customized aspheric treatment (OPDCAT) in the fellow eye comprised one part of the study. The second part of the study was a retrospective review of myopic LASIK using CATz in 84 eyes and LASIK using OPDCAT in 84 eyes. In the CATz-treated eyes, the preoperative mean spherical equivalent refraction was -4.06+/-1.69 diopters (D). In OPDCAT-treated eyes, the preoperative mean spherical equivalent refraction was -3.67+/-2.17 D. RESULTS: In the CATz-treated eyes, 95% of eyes achieved > or = 20/20 best spectacle-corrected visual acuity (BSCVA) with 15% gaining lines of BSCVA. In the OPDCAT-treated eyes, 94.5% of eyes achieved > or = 20/20 vision with 4.5% gaining lines of BSCVA. The difference in lines gained between CATz and OPDCAT in the retrospective component was statistically significant (P<.005). OPDCAT-treated eyes showed a statistically significant worsening in OPD root-mean-square (OPD-RMS), higher order wavefront error, and corneal asphericity (P<.005) compared to preoperative in the retrospective portion of the study. In the contralateral arm of the study, OPD-RMS value was significantly higher (P<.005) in the OPDCAT eyes than the fellow CATz-treated eyes. OPDCAT-treated eyes show a larger change in the Strehl ratio compared to the CATz-treated eyes (P<.005). CONCLUSIONS: The refractive outcomes were excellent and showed no clinically significant difference between CATz and OPDCAT treatments. The higher induction of aberrations with the OPDCAT ablations may be due to the fact that these treatments are based on Zernike polynomials to drive the ablation.

Adult↗

PubMedDate not supplied

Optimized prolate ablations with the NIDEK CXII excimer laser.

PURPOSE: To describe a novel excimer laser ablation algorithm, termed optimized prolate ablation (OPA), that uses both topography and ocular aberrometry and maintains or improves the natural corneal shape postoperatively. METHODS: A descriptive article outlining the theory behind this OPA algorithm. RESULTS: The theoretical changes to the ablation algorithm described in this article will produce a prolate cornea postoperatively. CONCLUSIONS: OPA treated eyes will have equal or better visual quality than preoperatively because age-related changes from lenticular spherical aberration are measured and treated.

Algorithms↗