Vector analysis of corneal astigmatism after scleral buckling surgery

Changes in axial length, central cornea thickness, and anterior chamber depth after rhegmatogenous retinal detachment repair

BACKGROUND

This study was designed to measure changes in anterior chamber depth (ACD), central cornea thickness (CCT), and axial length (AL) after scleral buckle (SB) surgery or pars plana vitrectomy (PPV) for the repair of rhegmatogenous retinal detachment (RD).

METHODS

We prospectively reviewed the records of 245 eyes of 245 patients scheduled to undergo SB surgery and 238 eyes of 238 patients scheduled to undergo PPV. ACD, CCT, and AL were measured by spectral-domain optical coherence tomography (SD-OCT) and biometry, before surgery as well as 6 and 12 months postoperatively.

RESULTS

For both SB and PPV surgeries, ACD was observed to decrease significantly postoperatively, with this trend continuing throughout the follow-up period (p < 0.005). CCT showed no significant difference after PPV or SB surgery. AL increased significantly after SB surgery but not PPV.

CONCLUSION

Our results show that SB surgery altered the shape of the eye by changing both ACD and AL. PPV resulted in altered ACD. These findings should elucidate the changes to be expected after SB and PPV surgeries.

A Prospective Study of Biometric Stability After Scleral Buckling Surgery

PURPOSE

To assess time to stabilization and factors associated with changes in biometric parameters after scleral buckling (SB).

DESIGN

Prospective case series.

METHODS

Seventeen eyes with primary rhegmatogenous retinal detachment (RRD) that underwent SB at the Singapore National Eye Centre were enrolled. SB surgery was performed using an encircling element and segmental buckle. Axial length (AL); anterior chamber depth (ACD), defined as the distance from the corneal epithelium to the anterior lens surface; anterior/posterior corneal curvature (K); and refraction were measured preoperatively and at week 1 and months 1, 3, 6, 9, and 12 postoperatively. Stability of each parameter was defined as the earliest time point at which there is no significant difference compared to its value at month 12.

RESULTS

AL increased (26.09 ± 1.46 to 26.51 ± 1.96, P = .01), ACD decreased (3.84 ± 0.47 to 3.32 ± 0.57, P < .001), and a myopic shift of 1.04 diopters (95% CI 0.03-2.05, P = .04) occurred at month 12. Anterior/posterior K were not significantly changed from baseline. AL stabilized at month 3 while ACD and spherical equivalent (SE) stabilized at week 1. Cryotherapy was associated with greater increase in AL (P = .001) and myopic shift (P = .02). More extensive segmental buckling was associated with greater increase in AL (P = .009) and myopic shift (P = .03).

CONCLUSIONS

Our study suggests that patients requiring cataract surgery after SB should have biometry performed no earlier than 3 months post SB surgery, and intraocular lens power calculation with a fourth-generation formula. A greater increase in AL and myopic shift was associated with cryotherapy and more extensive segmental buckling.

The Effect of Scleral Buckling Surgery on Corneal Astigmatism, Corneal Thickness, and Anterior Chamber Depth

PURPOSE

To evaluate the effect of scleral buckling surgery on corneal topography, corneal thickness, and anterior chamber depth.

METHODS

Thirty-two eyes of 32 patients who underwent encircling buckling surgery for rhegmatogenous retinal detachment were included in the study. Fellow eyes comprised the control group. Orbscan II topography system was used to determine the changes in corneal topography, corneal thickness, and anterior chamber depth before surgery and 1 week, 1 month, and 3 months after surgery. Statistical analyses used in the study were independent t test, paired t test, one way analysis of variance, and correlation analyses.

RESULTS

Postoperatively, mean central corneal astigmatism at 1 week, 1 month, and 3 months was 4.3 +/- 2.0 diopters (D), 3.3 +/- 1.6 D, and 3.1 +/- 1.0 D, respectively. The change between 1 week and 3 months was statistically significant. Central cornea was thickened at the first postoperative week. The thickness gradually decreased to the preoperative levels at 3 months. Anterior chamber depth decreased, and the anterior chamber remained shallow after the surgery. The comparison between preoperative (2.94 +/- 0.6 mm) and postoperative anterior chamber depth was statistically significant at 1 week (2.57 +/- 0.7 mm), 1 month (2.83 +/- 0.7 mm), and 3 months (2.73 +/- 0.6 mm).

CONCLUSIONS

Corneal changes after scleral buckling surgery were mild to moderate and the cornea almost resumed its preoperative parameters in 3 months' time. However, the anterior chamber remained shallow during 3 months of follow-up.

Efficacy of removal of buckle after scleral buckling surgery for retinopathy of prematurity

BACKGROUND OR PURPOSE: A series of encouraging reports over the past decade indicate that scleral buckling (SB) surgery may lessen or eliminate vitreoretinal traction in advanced retinopathy of prematurity (ROP). The effects of SB surgery on refraction and ocular growth, however, have not been demonstrated. We investigated the effects of postoperative removal of buckle in infants whose retinas were reattached in stage 4 ROP.

METHODS

Selected for study were 6 eyes of 3 patients whose retinas had been reattached by placing an encircling buckle, 2.5 mm in width, around the eye and whose buckles were subsequently removed. Axial lengths and refractive errors were compared before and after removal of the buckles. The patients were examined for at least 3 years after removal.

RESULTS

There was high myopia in all eyes treated for stage 4 ROP with SB. All retinas remained attached after removal of the buckle. Although there was a variable degree of increase in axial length, myopic refractive error tended to decrease after removal of the buckle.

CONCLUSIONS

There was some decrease in degree of myopia without resulting in retinal detachment or continued vitreous traction after buckle removal following SB surgery for ROP.

Topography after repair of full-thickness corneal laceration

PURPOSE

To characterize corneal topography after repair of full-thickness corneal laceration.

SETTING

Ophthalmic emergency room serving as a trauma referral center.

METHODS

Twenty-two eyes with full-thickness corneal lacerations were prospectively studied after standardized surgical repair. Computerized videokeratography was done 2 and 14 weeks after surgery, with the latter measurement corresponding to 6 to 8 weeks after all sutures were removed. Fellow uninjured eyes served as the control group.

RESULTS

Twenty eyes (91%) had a significant reduction in topographic distortion after suture removal. Mean corneal astigmatism, measured by simulated keratometry, was 10.70 diopters (D) +/- 5.90 D (SD) with sutures in place and 2.25 +/- 4.90 D after their removal (P < .005). Eighteen patients (82%) had 2.00 D or less of corneal astigmatism 6 to 8 weeks after all sutures were removed. The final distribution of topographic patterns was bow tie (50%), spherical/oval (36%), and irregular (14%). There was no significant correlation between laceration configuration (curvilinear, jagged, branched wound margins) and final topography. Lacerations that passed within 2.0 mm of the line of sight, however, were significantly more likely to have more than 2.00 D of final astigmatism. Mean central corneal power was 42.40 +/- 3.20 D in the injured eyes and 42.40 +/- 2.40 D in the uninjured fellow eyes.

CONCLUSION

Although high astigmatism is frequently produced by corneal sutures used to repair full-thickness lacerations, the cornea has a substantial topographic memory that results in a marked normalization of contour after suture removal.