Tutorial
Introduction
A Cataract Surgeon's Personal Experience with Cataract Surgery
Johnny L. Gayton, MD
Radial keratotomy (RK) surgery was performed on my left eye several years prior to developing bilateral cataracts. My markedly dominant left eye was distance corrected and my nondominant right eye was kept at near correction. I had previously enjoyed excellent uncorrected vision for several years. Unfortunately, I developed a severe case of epidemic keratoconjunctivitis (EKC) with marked corneal involvement in my left eye. This EKC reduced my best-corrected vision to 20/80, although my best-corrected vision in both eyes was 20/30. The EKC was unresponsive to lubricants and antibiotics, so steroid drops were instituted. The steroid drops gradually eliminated the subepithelial opacities, but when I tried to wean off the drops, the opacities recurred. I was steroid dependent for 2 years. Unfortunately, the steroids also caused an increase in intraocular pressure (IOP) requiring me at times to be on three topical IOP-lowering agents.
The next step in treatment included the use of nonsteroidal anti-inflammatory agents. First, FML (fluorometholone, Allergan), Flarex (fluorometholone acetate, Alcon), and Vexol (rimexolone ophthalmic suspension, Alcon) were used. However, none of these drugs controlled the corneal inflammation. Prednisolone was effective in preventing recurrences. Unfortunately, prednisolone also caused a severe rise in IOP. I preferred the results I experienced with Lotemax (loteprednol etabonate, Bausch & Lomb and Pharmos) in that it controlled the corneal inflammation without causing a significant rise in IOP.
Less than 2 years into trying to treat my EKC, I noticed an increasing multopia in my left eye. I had some multopia from the subepithelial opacities, but this was worse. When I used a card with a pinhole over my left eye in bright light, an obvious dark opacity was seen. This dark opacity was also noted when performing microscopic surgery. The opacity was relatively small and did not interfere with surgery. However, the increasing nighttime multopia with as many as five images and nighttime glare convinced me that I must have cataract surgery.
Because I had previously had RK surgery, the lens power calculation could not be calculated by the standard method using keratometry. Because RK alters the keratometry, the keratometry measurement must be adjusted. There are three methods for adjusting the keratometry in post-RK patients: the history method, the contact lens method, and the topography method. The topography method simply uses the central corneal power calculated by the topographer, and is usually the least accurate method.
The history method for adjusting the keratometry reading requires the pre-RK refraction and keratometry. If the pre-RK refractive error was at least 4 D, the pre-RK spherical equivalent is corrected for the 0-mm vertex distance/corneal plane. The change in refraction is then determined by the following calculation:
Corrected pre-RK spherical equivalent - post-RK spherical equivalent = change in refraction
The contact lens method for adjusting the keratometry reading involves obtaining an overrefraction with a rigid gas permeable contact lens close to a patient's keratometry reading. A plano lens with known base curve is used. A myopic shift in overrefraction indicates that the contact lens is stronger than the cornea, while a hyperopic shift in refraction indicates that the contact lens is weaker than the cornea. The spherical equivalents of the preoperative and overrefraction are determined and the change in refraction is calculated. The change in refraction is added to the base curve.
Corrected keratometry = (overrefraction spherical equivalent - post-RK spherical equivalent) + base curve.
In my case, the desired refraction was -1.5 D to -2 D. The manual keratometry was 40.87/42.00 x 90, and the simulated keratometry by topography was 41.51/42.55. The central topography power was 41.29.
Using the history method of calculation for adjusting the keratometry reading, the pre-RK spherical equivalent was -3.125, and the post-RK spherical equivalent was 0.875. The pre-RK average keratometry reading was 44.87. Using the history method formula yielded the following:
Corrected keratometry = [44.87] - [-3.125 - 0.875] = 40.87
Using the contact lens method yielded an overrefraction of 0.75 D, while the post-RK spherical equivalent was 0.88 D. The base curve was 41.00. The contact lens method formula determined the following:
Corrected keratometry = [0.75 - 0.88] + 41 = 40.87
The results of the power calculation formula (Holladay II) suggested that a 23 D lens is required for a predicted refraction of -1.41 D when using the uncorrected manual keratometry reading. Using the topography central power reading suggested a 23 D lens for a predicted refraction of -1.55 D. The history and contact lens methods produced the same corrected keratometry, which suggested a 24.5 D lens for a predicted refraction of -1.83 D. When the time came for my cataract surgery, a 24.5 D lens was implanted.
I started performing cataract surgery routinely in 1984. Because of my extensive experience with this approach, I wanted to have a surgeon who was comfortable with a temporal approach. I also wanted a surgeon who had used the AcrySof (Alcon, Ft. Worth, Texas) lens, because the AcrySof lens has been shown to have a decreased incidence of posterior capsule opacity.1 At my relatively young age, I wanted to keep my posterior capsule clear as long as possible. (Note: I had my surgery approximately 3 years ago and still do not have posterior capsule opacities.)
I also wanted a surgeon who had an excellent reputation for analyzing the cataract procedure and who performed a significant amount of cataract surgeries. Richard Mackool, MD, met all the criteria that I established for a surgeon to perform cataract surgery on me. On September 10, 1998, Dr. Mackool performed cataract surgery on me. A mild sedative was administered and the procedure was to be performed topically. Unfortunately, I had severe photosensitivity possibly due to the previous RK and EKC spots, as well as the posterior subcapsular cataract. Regardless, my photosensitivity resulted in a severe Bell phenomenon making Dr. MacKool's task much more difficult. He elected to inject intracameral lidocaine and increase my IOP enough to close the central retinal artery.
I remember everything turning black at one point. Obviously, the photosensitivity disappeared at that time. The cataract procedure continued unremarkably. At the point in which Dr. Mackool enlarged the incision for insertion of the intraocular lens (IOL), I felt some slight discomfort. I could see the lens optic and haptics as the IOL was inserted.
I could see immediately postoperatively. I began treatment with Voltaren (diclofenac sodium, Novartis Ophthalmics), Tobradex (tobramycin dexamethasone, Alcon), and Ciloxan (ciprofloxacin HCl, Alcon) drops along with Genteal (hydroxypropl methylcellulose, Novartis Ophthalmics) artificial tears. Dr. MacKool examined me the following day and found the eye to be in excellent condition. I was back at work the next day. Ten days later, I flew to Dr. Mackool's office in New York and had the second eye treated. I flew home the same day as that procedure and was checked at my own office.
I was satisfied with my postoperative results. My RK eye was corrected at near and my nondominant eye was made my distance eye. Currently, I enjoy excellent monovision. I wear glasses primarily for driving at night, performing plastic surgery, and reading in dim conditions. My left eye has a spherical equivalent of -1.75 D, and my right eye is plano.
I experienced significant dysphotopsia and glare for approximately 1 week. Since then, I have experienced no unwanted images and little glare. I only notice glare problems when direct sunlight or incandescent light catches me at just the right angle. Overall, I am extremely satisfied with the results of my cataract surgery.
Posted June 2001
- Martin RG, Kraff MC, Raanan M. Nd:YAG laser capsulotomy. In: Gills JP, Fenzl R, Martin RG, eds. Cataract Surgery: The State of the Art. Thorofare, NJ: Slack; 1998.