Anterior megalophthalmos is a rare hereditary condition with a constellation of findings that includes a horizontal corneal diameter greater than 13.0 mm (macrocornea), ciliary ring enlargement, anterior embryotoxon, mosaic corneal dystrophy, Krukenberg's spindle, hyper-deep anterior chamber, iris hypoplasia, large capsular bag, and lens subluxation.1,2 Cataract surgery in a megalophthalmic eye is challenging because of the compromised view, cavernous chamber, unusually large dimensions that alter the surgeon's prospective, thin peripheral cornea, and loose zonules. If each hurdle of the procedure is overcome, the surgeon must still confront a large lens that may lead to decentration of a standard intraocular lens (IOL) implanted in the capsular bag.
We report a surgical approach using a scleral tunnel incision, estimation of the capsulorhexis size, capsule staining, slow-motion microcoaxial phacoemulsification with torsional ultrasound, and a custom IOL designed for this very large eye.
A 43-year-old physician was referred with bilateral gradual loss of vision. On examination, the best corrected visual acuity (BCVA) was 20/160 in the right eye and 20/40 in the left eye; the refractive error was −4.75 +2.50 × 104 and −3.25 +3.50 ×75, respectively. The corneal diameter was 16.25 mm in the right eye and 16.50 mm in the left eye (Figure 1). Mosaic corneal dystrophy and posterior crocodile shagreen with dense Krukenberg's pigmentary spindles were present (Figure 2). The anterior chambers were cavernous (Figure 3), and each pupil measured 7.0 mm in ambient light. The pupils were slightly eccentric, with atrophy of the iris stroma and multiple transillumination defects. Each lens showed moderate nuclear sclerosis; the left lens was mildly subluxated (Figure 4). Gonioscopy revealed dense pigmentation on the trabecular meshwork. The ocular motility, visual fields, intraocular pressures, and fundi were unremarkable.
Pachymetry was 421 μm in the right eye and 424 μm in the left eye. Keratometry measurements were 41.00/43.27 @ 112 and 40.81/43.49 @ 82, respectively. With the IOLMaster (Carl Zeiss Meditec), the anterior chamber depth was 6.9 mm in the right eye and 6.7 mm in the left eye; the axial length was 28.09 mm and 27.69 mm, respectively. Ultrasound biomicroscopy was unavailable.
Because of the very large anterior segment dimensions, IOL companies were canvassed for assistance in designing a custom IOL for this patient. With assistance from Nick Mamalis, MD, an IOL with a 7.0 mm optic and an overall length of 16.0 mm was designed. Bausch & Lomb volunteered to manufacture the IOL in a 3-piece design with a silicone optic and a power of +11.00 diopters. The first eye was scheduled for surgery to be followed by the second eye several months later.
Using a retrobulbar block in the first eye and topical anesthesia in the second eye, a 4.0 mm 3-plane scleral tunnel incision was constructed. The anterior chamber was entered with a 2.2 mm diamond keratome; a vial of an ophthalmic viscosurgical device (OVD) (sodium hyaluronate 2.3% [Healon5]) was necessary to partially fill the chamber. The anterior capsule was stained with trypan blue (Vision Blue), and a caliper was used to mark a 7.0 mm zone on the cornea. Using the corneal marks as a guide, the capsulorhexis was completed with a bent 22-gauge needle, followed by gentle hydrodissection. Slow-motion microcoaxial phacoemulsification with torsional ultrasound was performed (Figure 5); the cortex was removed with a silicone irrigation/aspiration tip. The posterior capsule was vacuumed, and the capsular bag was expanded with another vial of the OVD. The incision was enlarged to 4.0 mm, and the custom IOL was folded and inserted without difficulty (Figure 6). The OVD was removed, the pupil was constricted with acetylcholine chloride (Miochol), and a 10.0 horizontal suture was passed to ensure a water-tight closure. The eye was dressed with prophylactic pilocarpine 2%, brimonidine (Alphagan), lantanoprost (Xalatan), timolol (Timoptic 0.5%), and moxifloxacin (Vigamox). A periocular triamcinolone (Kenalog) injection (1.0 cc) was given through the lower lid.
Postoperatively, the BCVA improved to 20/25 in the right eye and 20/25 in the left eye, with a refractive error of −0.25 +2.00 × 112 and +0.25 +3.00 × 78, respectively. The IOLs remained well centered without pseudophacodonesis. The patient, who was a surgeon, was very pleased with the visual result and was able to perform endoscopies within several days of surgery.
There are several challenges in performing cataract surgery in patients with megalophthalmos. The incision has to be carefully constructed because the cornea in these eyes is often quite thin. Barrett reported severe leakage of a clear corneal incision despite a small phaco and stab incision (presented as a video in the International Video Symposium of Challenging Cases and Complication Management, ASCRS Symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, May 2004). Therefore, in our patient, we made a scleral tunnel incision and sutured it. It is noteworthy that the stab incision leaked enough to require stromal hydration in each eye.
Because the corneal dystrophy and extreme anterior chamber depth may compromise visualization, we chose to stain the capsule with Vision Blue, similar to the case of Lee et al.,3 using a 3-step technique.4 However, establishing the proper capsulorhexis size can be difficult when all the landmarks and dimensions are abnormal. Therefore, we used an unpublished technique to determine the capsulorhexis size (Frederico Marques, MD, and Robert Osher, MD, 2003): In 10 patients with white cataract, the anterior capsule was stained with trypan blue. Following the capsulorhexis, the excised anterior capsule was placed on the corneal surface and the ratio of the diameter of the stained excised capsule to the diameter of the underlying stained intracameral capsulorhexis edge was determined. The white background of the cortex made the contrast easy to photograph, and the mean magnification was approximately 20%. Therefore, a caliper was set at 7.0 mm, placing 2 marks on the cornea to facilitate about a 5.5 mm capsulorhexis in this patient.
The phacoemulsification was uneventful, although the cortical behavior was stubborn, perhaps because of the mild zonular compromise. Although capsular tension rings were available, it was not necessary to implant one in either eye, as previously reported.5
The big challenge was selection of the IOL. Cases of IOL malposition with endocapsular fixation have been reported.5–8 Surgeons have tried to prevent this complication by implanting an iris-supported Binkhorst IOL,9 suturing an anterior chamber IOL,7 suturing the optic or haptic to the anterior capsule and iris,10 and placing an iris-clip IOL in the posterior chamber.3 Kwitko et al.6 experienced dislocation of a standard size posterior chamber IOL. As a result, a special Sinskey posterior chamber IOL with an optic of 7.0 mm and an overall length of 18 mm was implanted in the second eye. The authors recommended using a larger IOL diameter in patients with megalocornea.
We considered using an anterior or posterior optic capture technique to achieve stable centration of the IOL.11 We were fortunate that Bausch & Lomb was willing to manufacture a custom IOL for this patient. Unfortunately, the process took almost 1 year and the patient was unwilling to wait the same period of time for the second eye when we realized that a stronger power would likely achieve a residual refractive error closer to emmetropia. Nevertheless, he was pleased with the visual outcome and the IOLs have remained perfectly centered (Figure 7).
In summary, special considerations must be given to the patient with megalophthalmos who requires cataract surgery. While a candid discussion of the increased risk is necessary, it is likely that a well-planned approach will be successful.
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