Malpositioned and dislocated intraocular lenses : management, complications and surgical repositioning

Abstract

Cataract surgery (exchange of the non-transparent crystalline lens with an IOL) is the most frequent surgery in Sweden, accounting for more than 130000 surgeries per year. Therefore, complications associated with cataract surgery affect a significant number of patients. One of the complications is IOL dislocation, meaning that the IOL is not located at the central part of the optical zone, which often causes visual impairment. The overall aim of this thesis was to deepen knowledge about dislocated IOLs, especially surgery of out-of-the-bag and in-the-bag dislocated IOLs and management of uveitis-glaucoma-hyphema (UGH) syndrome.

Study I had a retrospective case-control design with a total of 32 patients, and included out-of-the-bag dislocated IOL. The aim was to evaluate the efficacy and safety of 3-piece IOL suturing to the iris. The case group (n=14; Iris group) underwent dislocated out-of-the-bag 3-piece IOL suturing to the iris. The control group (n=18; Exchange group) underwent IOL exchange with a new IOL sutured to the sclera. The groups were followed in the median of 13.5 (interquartile range (IQR) 10–20) and 12.5 (IQR 10–14) months, respectively. Best corrected visual acuity (BCVA) improved significantly in each group with no significant difference in either final BCVA or final intraocular pressure (IOP) between the groups. Complication frequency was similar in the groups. Surgically induced corneal astigmatism (SIA) and number of postoperative visits were significantly lower in the Iris group.

Study II, a prospective randomized clinical trial with a cross-sectional part, included in-the-bag dislocated IOL. A total of 177 patients were analyzed in this study. The aim was to evaluate three-dimensional (3-D) IOL position, refractive change, and IOL-induced astigmatism (IIA), also importance of capsular fibrosis on postoperative IOL position after IOL suturing to the sclera (2.5 mm behind the limbus) using 2 surgical methods: Ab Externo Scleral Suture Loop Fixation (Group A) and a modification, Embracing the Continuous Curvilinear Capsulorhexis (CCC), a technique created by L.A. (Group B). Additionally, the study evaluated the usefulness of swept-source anterior segment optical coherence tomography (SS–AS-OCT) for measuring 3-D IOL position. A total of 117 patients (117 eyes) with in-the-bag dislocated IOL were randomized into Group A (n=61) or Group B (n=56). The control group consisted of patients with ordinary pseudophakia (n=60). The median IOL tilt did not significantly differ between Group A (7.8°, IQR 5.9°–12.0°) and Group B (8.3°, IQR 6.4°–10.8°) but each group was significantly different from the ordinary pseudophakia (5.4°, IQR 3.9°–7.1°) by the mean of 3.75° (CI (confidence interval) 2.54°–4.95°). The direction of IOL tilt was inferotemporal in 87%–87.5% of patients in each of the three groups, and a mirror symmetry was observed between the left and right eyes. IOL surgery resulted in significant myopic shift. In eyes without capsular fibrosis, the median IOL tilt was 15.5° (IQR 7.8°–21.7°) in Group A (n=7) and 7.0° (IQR 6.6°–11.4°) in Group B (n=5) although without a statistically significant difference. IIA was 0.075 D for each degree of IOL tilt, which was statistically significant. Five patients (three in Group A and two in Group B, of which one IOL was dislocated by intraocular gas) were re-operated after their one-month follow-up visit. IOL position could be measured with SS–AS-OCT in all cases if the IOL could be seen in the pupil. It was also possible to measure and quantify the capsular bag thickness.

Study III focused on UGH syndrome, and had a retrospective case-control design with a cross-sectional part and a descriptive part. A total of 213 patients were included. The study comprised both out-of-the-bag and in-the-bag dislocations as well as other types of IOL malpositions; however, all causing UGH syndrome. The study aimed to evaluate the effect of UGH treatment, a need for IOP-lowering treatment, clinical manifestation (including iris-IOL contact signs) and usage of blood thinners (anticoagulants and antiaggregants), also, which examination–clinical, AS-OCT, or ultrasound biomicroscopy (UBM)–was the most effective tool to diagnose UGH syndrome. Three groups of patients were compared: UGH syndrome (n=71), dislocated IOL without UGH (n=71) and uncomplicated pseudophakia (n=71). Surgical treatment was effective in approximately 77% of cases. IOP and BCVA improved significantly in the operated patients but not in the non-operated patients. In total, 51% of all patients (57% of operated patients) needed IOP-lowering therapy after UGH resolution, and IOP≥22 mmHg at the first (1st) hemorrhage was the only significant predictor identified for this. Pseudophacodonesis (IOL-donesis) was seen in 22.5% of patients at the beginning of UGH syndrome, and was significantly more frequent than in the Pseudophakic group. Transilluminating iris defects (TID) in the UGH group were not more frequent than in the Dislocated group at the beginning of UGH. However, the shape of TIDs differed significantly: haptic or optic edge formed TIDs were seen more frequently in the UGH group. Patients with UGH syndrome did not use blood thinners more frequently than patients in Dislocated group, except Warfarin (Waran®). Examination on a slit-lamp, AS-OCT, and UBM showed iris-IOL contact in 97%, 19%, and 21% of patients, respectively.

Conclusions: Suturing out-of-the-bag dislocated 3-piece IOL to the iris is a safe and effective surgical treatment with less SIA and fewer postoperative visits to an ophthalmologist than IOL exchange. Suturing in-the-bag dislocated IOL to the sclera results in good IOL position with both surgical methods, although the position differs from the normal pseudophakia by approximately 3.75° which has little clinical significance as IOL-tilt induced astigmatism is low. However, IOL suturing to the sclera induces myopic shift in cases when the IOL is sutured 2.5 mm behind the limbus. A new study with more patients without capsular fibrosis would show whether IOL position is better with the modified method than with the traditional one in this subgroup. SS–AS-OCT is useful for 3-D IOL position quantification after IOL repositioning. Surgical treatment does not guarantee resolution of UGH syndrome, though BCVA results are better than with conservative treatment. IOL-donesis is a risk factor for UGH syndrome. The impact of Warfarin (Waran®) on UGH development should be investigated further, although other blood thinners probably do not increase the risk for UGH syndrome. TIDs are not specific to UGH syndrome unless they are formed like the haptic or optic edge. Every second patient may need IOP-lowering therapy; IOP≥22 mmHg at the first hemorrhage predicts the need for IOP-lowering treatment in a long run (after UGH resolution). Follow up time should be long after UGH resolution. Clinical examination was more useful for detecting iris-IOL contact than AS-OCT or UBM in study III.