Influence of Ocular Features and Incision Width on Surgically Induced Astigmatism After Cataract Surgery

Abstract

Reducing limbal incision width and considering patient age, the meridian and magnitude of corneal astigmatism, anterior chamber depth, axial length, and intraocular pressure, and adjusting the flattening component of SIA input for toric intraocular lens power calculation could potentially improve the astigmatism control in refractive lens surgery.

Biomechanical changes in the cornea following cataract surgery: A prospective assessment with the Corneal Visualisation Scheimpflug Technology

“…Although corneal stiffness is reduced following surgery, there were no significant differences in stiffness that could be detected with different corneal incision sizes. Larger corneal incisions are associated with more surgically induced astigmatism after cataract surgery; however, incision size in the current study was independent of corneal stiffness changes . The peripheral location of the relatively small corneal incisions is the likely reason that no significant changes were detected by the Corvis‐ST.…”

“…Larger corneal incisions are associated with more surgically induced astigmatism after cataract surgery; however, incision size in the current study was independent of corneal stiffness changes. 22 The peripheral location of the relatively small corneal incisions is the likely reason that no significant changes were detected by the Corvis-ST. This finding is consistent with similar results noted when assessing biomechanical changes induced by corneal-scleral incisions.…”

“…19,20 These changes result in decreased IOP following surgery, in eyes with or without glaucoma, and/or ocular hypertension. 19,21,22 Mean IOP reductions of 1.3 to 3.3 mmHg have been previously reported at 3-mo follow-up in healthy patients, those with ocular hypertension and those with narrow angles. 14,19,20 A larger reduction in post-phacoemulsification IOP is found in The net pressure at first applanation (calculated as the difference between the air-puff pressure at the corneal surface and the biomechanically corrected IOP), divided by the deflection amplitude Biomechanical corrected IOP 9 bIOP 2016 Corvis-ST IOP is corrected by accounting for patient age and central corneal thickness eyes with narrow angles; however, little is known about the effect of corneal ectasia on this phenomenon.…”

“…Surgical trauma during cataract surgery is associated with increased anterior chamber pressure, resulting in physical and biochemical changes in the cornea and anterior segment, which persist for up to 1 y . These changes result in decreased IOP following surgery, in eyes with or without glaucoma, and/or ocular hypertension . Mean IOP reductions of 1.3 to 3.3 mmHg have been previously reported at 3‐mo follow‐up in healthy patients, those with ocular hypertension and those with narrow angles .…”

How to get Accuracy in Intraocular Lens Calculation in Normal and Extreme Cases

“…Detecting inconsistent measurements during biometry It is important to note that the SIA increases with increased corneal astigmatism so the SIA or FE is not constant; for a 1 D increase in astigmatism the SIA increases by 0.37 D. 6 The SIA also varies on whether the incision is placed on the steep or flat meridian. 7 Retrospective analyses of phaco incisions separately for each eye can determine the amount of flattening at specific corneal meridia (Figure 2).…”