ABSTRACT
Introduction: Modern day cataract surgery is aimed at giving optimal catarefractive outcome . This study was inspired by a chance finding of high astigmatic reading on performing retinoscopy three weeks after surgery in a female who underwent manual small incision cataract surgery. Aim of study: To study effect of scleral tunnel incision at different locations on pre-existing astigmatism ,and to calculate surgically induced astigmatism there from . Design: The scleral tunnel incision is known to undergo changes upto six weeks after cataract surgery .If pre operative value and post operative values at the end of six weeks are known ,SIA can be calculated. All patients operated free of cost for cataract are implanted an all PMMA non foldable 6.0mm intraocular lens hence we chose a six mm frown incision. From our study we aim to give cut off values of native astigmatism to chose incision site in order to provide least residual astigmatism, since this group of patients being non affording cannot undergo any additional surgical procedure to get astigmatism corrected . The higher order post cataract surgery residual error degrades quality of image ,hence accentuation of native error by SICS is non justifiable . Rather,our aim should be to regress existing error by 50% -75%. Method: In 150 eyes undergoing cataract surgery in the department of Ophthalmology, Aurobindo Institute Of Medical Sciences under eye camp, the preoperative keratometric values in vertical and horizontal axis were noted .At the end of six weeks after cataract surgery performed by 6mm incision at superior, superotemporal and absolute temporal locations , keratometry readings were noted again along the principle meridia .SIA was calculated from these two readings. At the end of six weeks keratometry and retinoscopy weres done. Result: From the study it was concluded that location of incision in the eye has a bearing on existing astigmatic error . A regression (or accentuation) in the existing error is dependent on the incision site and the magnitude of pre-existant error. With superior and absolute temporal scleral tunnel incision , SIA average was 0.77 Dioptres while with BENT( between nine and twelve) clock hours it was lesser (0.68 Dioptres) Except in thirteen eyes who accepted cylindrical lens in oblique meridia, all others accepted glasses in primary meridia. Conclusion: For upto 1 D astigmatism, ATR or WTR, placement of incision on steeper axis should be the choice. For WTR, of any degree, a superior location should be the choice. For ATR amounting to 1.25D, a superotemporal incision offers best results. For higher ATR absolute temporal location should be the choice if regression in astigmatism is desired.
ABSTRACT
PURPOSE: This investigation was performed to evaluate the surgically induced astigmatism of no-stitch frown incision with 4.0 mm chord length, which was compared with no-stitch 3.2 mm straight incision. METHODS: Sixty eyes, which could be observed for 3 months, were divided into two groups. Both groups were composed of 30 eyes. Group 1 - a semicircular frown incision with 4.0 mm chord length was made 1 mm posterior and most convex to limbus. Group 2 - a 3.2 mm straight incision was made 2 mm posterior to limbus. No-stitch was done in both groups. The corneal astigmatism was evaluated at postoperative 1st day, 1st week, 2nd week, 1st month, 2nd month and 3rd month with Bausch & Lomb keratometry, calculated by values derived from Cravy's vector method and statistically analyzed by Student t-test. RESULTS: The change of surgically induced astigmatism in group 1 was 0.52 D, 0.45 D, 0.43 D, 0.38 D, 0.40 D, and 0.39 D at 1st day, 1st week, 2nd week, 1st month, 2nd month, and 3rd month, respectively. In group 2, it was 0.83 D, 0.72 D, 0.65 D, 0.52 D, 0.50 D, and 0.49 D at the same intervals. These differences of astigmatic change were not statistically significant(p>0.05). CONCLUSION: The astigmatic change in a no-stitch frown incision with 4.0 mm chord length was not enough to comparable with that of a no-stitch 3.2 mm straight incision. We could safely use PMMA intraocular lens by no-stitch frown incision. So, this method has some advantages over small incision with foldable intraocular lens.
Subject(s)
Humans , Astigmatism , Cataract , Lenses, Intraocular , Polymethyl MethacrylateABSTRACT
To evaluate surgically induced astigmatism in cataract surgery, we studied retrospectively a series of 30 eyes with 6.5mm sutureless frown incision(Group 1) and 30 eyes with linear scleral tunnel incision and 3 interrupt sutures using 100 nylon(Group 2). In all cases phacoemulsifications were performed and posterior chamber lenses were implanted. Group 1 showed the against-the-rule astigmatism at postoperative 2 week, and then the change of the astigmatism was minimal and still against-the-rule by postoperative 6 week and 3 month. In contrast, Group 2 showed with-therule astigmatism at postoperative 2 week and then showed the against-the-rule by postoperative 6 week and 3 month. There was no significant difference in the proportion of corrected visual acuity of 0.5 or better between two groups at postoperative 3 month, while uncorrected visual acuity of 0.5 or better was 93.3% in group 2, and 30.0% in group 1 at postoperative 3 month. In this study, it was found that the pattern of surgically induced astigmatism and uncorrected visual outcome in cataract surgery were different according to incision and suture techniques.