Nomogram for astigmatic keratotomies with Clear Corneal Phako Surgery

Louis D. Nichamin, MD, Laurel Eye Clinic, Brookville, PA

If astigmatic status is

1. "spherical": (+0.75x90 <-> +0.50x180)

Use incision design : "neutral" viz. temporal clear corneal incision, 3.5mm or less, single plane, just anterior to vascular arcade

2. "against-the-rule": steep axis 0 - 30^o / 150 - 180^o

Intraoperative keratoscopy determines the exact incision location. The temporal incision is made by first creating a two-plane, grooved phako incision (600μ depth), which is then extended to the appropriate arc length at the conclusion of surgery.

Pre-op cylinder		30-40 yr	41-50 yr	51-60 yr	61-70 yr	71-80 yr	81–90 yr	> 90 yr
+0.75 to +1.25	Nasal limbal arc only						35
	Paired limbal arcs on steep axis	55	50	45	40	35
+1.50 to +2.0	Paired limbal arcs on steep axis	70	65	60	55	45	40	35
+2.25 to +2.75	Paired limbal arcs on steep axis	90	80	70	60	50	45	40
+3.00 to +3.75	Paired limbal arcs on steep axis	↓to 8mm; 90	↓to 8mm; 90	85	70	60	50	45
		degrees of arc to be incised

3. "with-the-rule": steep axis 45 - 145^o

"neutral" temporal clear corneal incision along with the following peripheral arcuate incisions

Pre-op cylinder		30-40 yr	41-50 yr	51-60 yr	61-70 yr	71-80 yr	81–90 yr	> 90 yr
+1.0 to +1.50	Paired limbal arcs on steep axis	50	45	40	35	30
+1.75 to +2.25	Paired limbal arcs on steep axis	60	55	50	45	40	35	30
+2.50 to +3.00	Paired limbal arcs on steep axis	70	65	60	55	50	45	40
+3.25 to +3.75	Paired limbal arcs on steep axis	80	75	70	65	60	55	45
		degrees of arc to be incised