CataractCoach™ 2563: cataract surgery in Axenfeld-Rieger syndrome скачать в хорошем качестве

CataractCoach™ 2563: cataract surgery in Axenfeld-Rieger syndrome

A century ago, Dr Axenfeld described a series of patients with congenital abnormalities of the anterior segment of the eye including anterior displacement of Schwalbe’s line, termed posterior embryotoxon, with anterior iris adhesions. Shortly thereafter, Dr Rieger noted more iris abnormalities such as corectopia, polycoria, and iris atrophy in these patients along with systemic deformities of the teeth and facial bones. Due to the dysgenesis of the anterior segment, the eye is prone to more pathology such as development of glaucoma due to irregular angle anatomy. Fortunately, Axenfeld-Rieger syndrome is rare and the degree of structural abnormalities can vary along a spectrum from mild to severe. This patient is referred to our clinic for cataract surgery and a considerable amount of time was spent evaluating the eye with care taken to detect the presence of confounding factors which could complicate the procedure. The patient was noted to have an unusual corneal shape which appeared somewhat rhomboid (Figure 1). The posterior embryotoxon was visible in certain areas of the cornea and notably there was corectopia with decentration of the pupil upon dilation due to an area of iris atrophy. No glaucoma was present and the angle anatomy looked reasonable with only a few areas noted to have iris strands adherent to Schwalbe’s line. In cases of Axenfeld-Rieger, it is common to have zonular laxity with focal areas of zonular absence, particularly in the area of iris atrophy. While our patient seemed to have a normal degree of zonular support, this is better assessed during surgery. For this reason, we arranged to have additional instrumentation available in the operating room such as capsule hooks, a capsular tension ring, a capsular tension segment, and the appropriate sutures. This patient is also highly myopic with a long axial length and desired to maintain a moderate degree of myopia to allow for unaided near vision. IOL calculations were performed for the patient’s preferred refractive target and a toric monofocal IOL was chosen as the first choice. We also arranged to have a three-piece monofocal IOL, which only comes in non-toric versions, available as a back-up plan. In the operating room, we started with topical tetracaine and intra-cameral preservative-free lidocaine for anesthesia, along with some mild systemic sedation with midazolam. If the case became more complicated we could always supplement that with a sub-Tenon’s administration of additional local anesthetics to achieve analgesia and akinesia. The incision was made temporally since that was the area of the cornea which was furthest from the visual axis. A superior incision in this case would be closer to the visual axis and that would likely induce more astigmatic effect. The initial creation of the capsulorhexis gives very important clues as to zonular laxity if we start it by puncturing the lens capsule with our forceps. If we use a sharp needle or cystotome instead, there is little feedback as to how taut the anterior capsule is. Fortunately, the zonular support seemed quite normal and we could proceed with the capsulorhexis. Importantly, the capsulorhexis is centered on the capsule and not within the pupil. Because of the asymmetric pupil dilation, we want to avoid using the pupil margin as a guide for the capsulorhexis because it would result in a misaligned anterior lens opening. (Figure 2) The nucleus removal went smoothly in this case, using a phaco chop variation. During cortical clean-up care was taken to observe the capsulorhexis to ensure that it did not move. For a full 360 degrees the zonular support was strong so a capsular tension ring was not needed. We implanted a toric monofocal IOL which was aligned at the appropriate axis to address the corneal astigmatism. Because of the care taken to create the capsulorhexis, there was a complete 360 degree overlap of the IOL optic which was well centered in the patient’s visual axis. The patient achieved an excellent post-operative outcomes and healed well from the surgery. She is being referred back to retina and glaucoma colleagues who will follow her longitudinally. For this patient, fortunately the degree of ocular abnormalities from Axenfeld-Rieger syndrome was limited and the cataract surgery was uneventful for both eyes. Since this is a rare condition, occurring in less than 1 in 100,000 people, I may not see another patient with this condition in the second half of my career.