Lens - Cataract Surgery, Complications and IOLs MCQs

Toric IOLs have an integral cylindrical refractive component to compensate for pre-existing corneal astigmatism . The main potential problem is rotation within the capsular bag (rare), and may be corrected by early surgical repositioning. Reference: Yanoff and Duker 4th edition 368

Endophthalmitis is the most dreaded and worst possible complication of cataract surgery. It is a suppurative inflammation starting from the vitreous which extends to all the parts of the eye except the sclera . If the sclera also becomes involved , the condition is then called as panophthalmitis . Reference: Yanoff and Duker 4th edition 724/725

Complications in the early postoperative period include wound leak, shallow anterior chamber, persistent or nonhealing epithelial defect, secondary glaucoma, graft oedema, uveitis, graft infection, inflammatory ‘sterile’ suture infiltrates and primary graft failure. In the late postoperative period (after 3 weeks), complications include graft rejection, graft infection, secondary glaucoma, loose sutures and high astigmatism. Very late complications (after 1 year) include graft rejection and wound dehiscence from minor trauma and recurrence of the primary disease. Reference: Parson’s diseases of the Eye-Chap 12 – Diseases of Cornea

Ans. A. ECCE + IOL Traumatic cataract in children is a common cause of unilateral loss of vision. Penetrating injuries are usually more common than blunt injuries. At the time of presentation after trauma to eye, primary repair of the corneal or scleral wound is usually preferred, Cataract surgery GCCE) with IOL implantations is performed later following complete evaluation of damage to the intraocular structures by ancillary methods such as B-scan ultrasonography.

Ans, B. Ciliary artery Expulsive hemorrhage after cataract extraction or glaucoma surgery = Rupture of ciliary artery. Expulsive hemorrhage in Retinal/Vitrous operation = Direct trauma to choroidal or vortex vein.

IOL implantation has the following advantages: Minimal after-care of patient Minimum aniseikonia (difference in image size seen by the eyes) Rapid return of binocularity and Normal peripheral vision Reference: Parson ch 8, P. 85

The lens power formula is dependent on axial length (in millimetres) and keratometry (in dioptres) as follows: Lens power = A − 2.5 (axial length) − 0.9 (average keratometry) A higher 'A-constant', 'decreased axial length', or 'decreased keratometry' readings would result in the calculation of a stronger lens. Moving a convex (plus) lens more anteriorly in the eye and away from the nodal point also effectively increases its power. Reference: Khurana Optics 2/e, P. 45

A number of formulas have been developed to calculate the IOL power after LASIK and refractive surgery, including the Aramberri Double K method, clinical history method, Masket method, and others. These rely upon pre- and postoperative refractions and keratometry, the LASIK treatment, and adjustments to these measurements. Although corneal thickness may influence the curvature of the cornea, the actual corneal curvature measurements and refractions are the most useful in the calculations for lens power post-LASIK. Reference: Khurana Optics 2/e, P. 51