Comparison of Clinical Outcomes of Iris Fixation and Scleral Fixation as Treatment for Intraocular Lens Dislocation




Purpose


To compare the efficacy and safety of iris fixation with scleral fixation in surgical repositioning of dislocated intraocular lenses (IOLs).


Design


Retrospective, consecutive, comparative interventional case series.


Methods


setting : Referral hospital. study population : Seventy-eight consecutive patients who underwent surgical repositioning of dislocated intraocular lenses using suturing to the sclera or iris. intervention : Forty-four eyes of 44 patients underwent scleral fixation and 35 eyes of 34 patients underwent iris fixation of dislocated intraocular lenses. main outcome measures : Visual acuity, refractive stability, operation time, and perioperative complications, including recurrence of IOL dislocation.


Results


Corrected distance visual acuity (CDVA) improved significantly 1 month postoperatively in both groups ( P < .01 each), and remained stable for 12 months. One week postoperatively, however, CDVA improved significantly in the scleral fixation ( P = .040) but not in the iris fixation ( P = .058) group. The amount of refractive error significantly diminished 1 day after surgery ( P = .028 in the scleral fixation and P = .046 in the iris fixation group). For the astigmatic components, Jackson crossed cylinders equivalent to conventional cylinders of positive power at axes of 0 degrees ( J0 ) and 45 degrees ( J45 ), J45 differed significantly in the scleral fixation and iris fixation groups ( P = .009), whereas J0 was similar ( P > .05). Operation time was significantly shorter ( P = .0007), while immediate postoperative inflammation was significantly more severe ( P = .001), in the iris fixation than in the scleral fixation group. Recurrence rates were similar ( P > .05), but the mean time to recurrence was significantly shorter in the iris fixation than in the scleral fixation group ( P = .031).


Conclusions


Iris fixation and scleral fixation techniques had similar efficacy in the repositioning of dislocated intraocular lenses. Although operation time was shorter for iris fixation, it had several disadvantages, including induced astigmatism, immediate postoperative inflammation, earlier recurrence, and less stable refraction.


Intraocular lens (IOL) dislocation is a known complication of cataract surgery, with an incidence ranging from 0.2% to 3%. The actual incidence rate may be even higher, owing to the large numbers of patients who have undergone cataract surgery and the increasing trend in IOL dislocation cases in recent years.


IOL dislocation may be treated by removal of the dislocated IOL and implantation of a new IOL. An anterior chamber (AC) or iris-claw lens can be implanted into the AC, or a posterior chamber (PC) IOL can be implanted into the PC, with suturing to the sclera or iris. IOL exchange, however, may have a higher rate of complications (owing to large incisional wounds and longer operation times) than other treatment options, including repositioning of a dislocated IOL using scleral or iris fixation in the globe as a closed system.


Repositioning of a dislocated IOL using scleral fixation carries potential risks, including refractive instability owing to lens tilt and decentration; intraocular hemorrhage owing to the passage of a needle through vascular uveal tissue; and suture breakage or endophthalmitis owing to connecting the suture material outside. Iris fixation also has potential complications, including iris chafing, pigment dispersion, chronic inflammation, progressive peripheral anterior synechia formation, and photic phenomena such as glare or halo due to pupillary distortion. To date, there is insufficient evidence comparing surgical and ocular outcomes of these 2 treatment options for IOL repositioning. This study therefore compared the clinical outcomes, including efficacy and complications, of iris and scleral fixation in patients undergoing surgical repositioning of dislocated intraocular lenses.


Patients and Methods


The study protocol, which complied with the provisions of the Declaration of Helsinki, was approved by the Institutional Review Board of Haeundae Paik Hospital (No. 129792-2014-059) before the start of this study.


Participants


This retrospective, consecutive, comparative interventional case series was performed using 44 eyes of 44 patients who underwent scleral fixation (the scleral fixation group) and 35 eyes of 34 patients who underwent iris fixation (the iris fixation group) of a dislocated IOL between January 1st 2011 and March 31st 2014. All medical records were obtained from the Haeundae Paik Hospital database and patients were identified based on the International Classification of Diseases 10th version using the code T85.2 for mechanical complication of intraocular lens. One hundred twenty patients with dislocated IOL were identified. Of these 120 patients, 42 patients underwent IOL exchange surgery and were excluded. Therefore, the remaining 78 patients who underwent either scleral or iris suture fixation of dislocated IOL were included in this study.


Surgical Techniques


All operations were performed by 2 experienced surgeons (K.H.K. and W.S.K.) using a standardized procedure. The eyes of patients were preoperatively instilled with 0.5% tropicamide, 0.5% phenylephrine, and flurbiprofen for pupillary dilation, followed by topical anesthesia with 0.5% proparacaine hydrochloride. Postoperative topical treatment included 0.5% moxifloxacin, flurbiprofen, and 0.1% fluorometholone.


All patients in the scleral fixation group underwent surgical repositioning of the dislocated IOL using the ab externo suture loop retrieval and fixation technique. After identification of the haptic axis, a limbal paracentesis site was prepared 180 degrees from the planned scleral suture site, followed by conjunctival and Tenon capsule dissection. A long curved needle with a 10-0 propylene suture (PC-7; Alcon, Fort Worth, Texas, USA) was used to enter the eye perpendicular to the sclera and 1.5 mm posterior to the limbus, then passed under the haptic in the AC. The needle was docked to a 27 gauge needle, which was inserted through the paracentesis on the opposite side and retrieved outside the AC while guiding the suture needle. The 27 gauge needle was inserted into the AC and over the haptic through the sclera 1.0 mm adjacent to the previous entry site, and docked with the 10-0 Prolene needle from the paracentesis to create a loop encircling the haptic. The retracted suture was tightened, tied outside the eye, and buried intrasclerally, followed by conjunctival closure. The same procedure was used for the other haptic.


Dislocation of the IOL was corrected in the iris fixation group using the McCannel suture technique. A 10-0 propylene suture on a long curved needle (PC-7; Alcon) was used to suture the IOL to the iris. If necessary, the IOL was dislodged anteriorly from the capsule using a spatula, resulting in a haptic within the ciliary sulcus. After pupillary constriction with acetylcholine hydrochloride (Miochol; Bausch & Lomb, Irvine, CA, USA), the optic was prolapsed above the iris plane and captured by the pupil. While a Barraquer iris spatula below the optic was used to tent the haptic against the iris, the needle was passed through the iris and below the haptic. The needle was introduced into the AC through the cornea and paracentesis parallel to the haptic; after exiting from the AC, the suture was used to tie a knot outside the eye. The suture knot was retrieved into the AC after external shortening. The other haptic was treated in the same way.


Data Collection and Analysis


Data retrospectively retrieved from the database included patient demographics, type of dislocation, interval between IOL dislocation and surgery, surgical technique used to correct the dislocation, visual acuity, intraocular pressure, refraction, keratometry, topography, corneal endothelial cell count, and perioperative complications, including the degree of AC reaction, recurrence rate, and interval between operation and recurrence. Visual acuity, measured using a Snellen chart, was converted to the logarithm of the minimal angle of resolution (logMAR) for analysis. Refractive errors were analyzed with the power vector method using 3 fundamental dioptric components: mean spherical equivalent power ( M ), and Jackson crossed cylinders equivalent to conventional cylinders of positive power at axes of 0 degrees ( J0 ) and 45 degrees ( J45 ). The Pythagorean length of the vector of these 3 components was used as a measure of overall blurring strength to compare changes in degree of refractive error; and the lengths of 2 components, J0 and J45 , were used to compare the amounts of astigmatism. AC reaction degree had been documented as standardized grades (0–4) during each examination of AC cells and flare, according to the grading scale proposed by the Standardization of Uveitis Nomenclature working group. Therefore each grade was converted to a number and trace amounts of AC cells were regarded as 0.5 for analysis.


Statistical Analysis


All statistical analyses were performed using SPSS version 17.0 (SPSS Inc, Chicago, Illinois, USA). Continuous variables were compared using independent t tests, Wilcoxon signed rank tests, and Mann-Whitney U tests, and categorical variables were compared using Pearson χ 2 tests. P < .05 was considered statistically significant.




Results


Patient Characteristics


There were no significant differences in age, sex, and laterality between the scleral and iris fixation groups ( P > .05 each, Table 1 ). In-the-bag dislocation was observed in 43.2% of eyes (19/44) in the scleral fixation group and 42.9% (15/35) in the iris fixation group ( P > .05). Operations in the scleral and iris fixation groups were performed at a mean of 1.4 ± 1.9 and 1.1 ± 1.4 months, respectively, from the onset of IOL dislocation, and mean follow-up durations after surgery were 16.6 ± 6.6 months (range, 0.73–31.8 months) and 16.3 ± 8.1 months (range, 0.17–39.3 months), respectively ( P > .05). The proportions of the 2 types of procedures were similar for the 2 surgeons (45.6% vs 61.9% for scleral fixation and 54.4% vs 38.1% for iris fixation, P > .05).



Table 1

Baseline Demographic and Ocular Characteristics of Patients Undergoing Iris Fixation or Scleral Fixation as Treatment for Intraocular Lens Dislocation

















































Scleral Fixation Group Iris Fixation Group P
Eyes/patients 44/44 35/34
Age at operation (mean ± SD, y) 61.2 ± 10.9 56.9 ± 13.1 .13 a
Sex (M/F) 32/11 26/8 .84 b
Laterality (OD/OS) 21/23 17/18 .94 b
Dislocation type (ITB/OTB) 19/25 15/20 .98 b
Onset from previous cataract surgery (mean ± SD, mo) 13.80 ± 23.81 12.15 ± 32.16 .90 c
Onset to corrective operation (mo) 1.4 ± 1.9 1.1 ± 1.4 .91 c
Follow-up (mean ± SD [range], mo) 16.6 ± 6.6 (0.73–31.8) 16.3 ± 8.1 (0.17–39.3) .52 c

ITB = in-the-bag; OD = right eye; OS = left eye; OTB = out-of-the-bag.

a Independent t test.


b χ 2 test.


c Mann-Whitney U test.



Visual Acuities


Visual acuity was significantly improved after surgery in both groups ( Figure 1 ). One week after surgery, corrected distance visual acuity (CDVA) was 0.38 ± 0.09 and 0.42 ± 0.09 logMAR units in the scleral and iris fixation groups, respectively. The change from mean preoperative CDVA of 0.57 ± 0.10 was significant in the scleral fixation group ( P = .040), but the change from mean preoperative CDVA of 0.58 ± 0.09 was not significant in the iris fixation group ( P = .058). After 1 month, the CDVA in both the scleral and iris fixation groups improved significantly, to 0.19 ± 0.04 ( P = .0002) and 0.25 ± 0.07 ( P = .0001), respectively, and remained stable for 12 months. There were no between-group differences throughout the follow-up period ( P > .05).




Figure 1


Changes in postoperative visual acuity over time after iris or scleral fixation as treatment for intraocular lens dislocation. The corrected distance visual acuity (CDVA) was significantly improved after surgery in both groups, except for an insignificant change in the iris fixation group 1 week postoperatively. After 1 month the CDVA in both groups improved significantly and remained stable for 12 months. There was no between-group difference throughout the entire follow-up ( P > .05, Mann-Whitney U test). LogMAR = logarithm of the minimal angle of resolution; Preop = preoperative day; * Wilcoxon signed rank test.


Refractive Stability


Refractive errors were significantly reduced postoperatively in both groups. Blurring strength, representing the amount of refractive error, improved from 3.94 ± 0.67 preoperatively to 2.06 ± 0.34 1 day after surgery in the scleral fixation group ( P = .028) and from 5.09 ± 0.75 to 2.90 ± 0.47 in the iris fixation group ( P = .046, Figure 2 , Top left). No subsequent changes through 12 months were observed in the scleral fixation (2.16 ± 0.22) and iris fixation (2.29 ± 0.25) groups ( P > .05) and no between-group differences were observed throughout follow-up ( P > .05).




Figure 2


Refractive outcomes after iris or scleral fixation as treatment for intraocular lens dislocation. (Top left) Changes in postoperative blurring strength over time. Blurring strength, representing the amount of refractive error, improved after surgery in both groups. (Top right) Changes over time in postoperative astigmatic components, such as Jackson crossed cylinders equivalent to conventional cylinders of positive power at axes of 0 degrees ( J0 ) and 45 degrees ( J45 ). Two-dimensional plot ( J0 , J45 ) using measurements at each follow-up visit shows that fewer astigmatic errors were observed in the scleral fixation than in the iris fixation group during follow-up. (Bottom left) Changes in amount of astigmatism over time. The amount of astigmatism, represented by the Pythagorean length of astigmatic components ( J0 and J45 ), increased significantly for 1 month postoperatively in the iris fixation group, but decreased to baseline level at 3 months and remained stable until 12 months. (Bottom right) Postoperative refractive change over time from the measurement 1 week postoperatively. The iris fixation group showed significant hyperopic change from 1 week to 12 months, whereas the scleral fixation group was stable after surgery. Preop = preoperative day; * Wilcoxon signed rank test.


Fewer astigmatic errors were observed in the scleral than in the iris fixation group during follow-up ( Figure 2 , Top right). Mean postoperative length of component J45 differed significantly in these 2 groups (0.04 ± 0.03 vs 0.23 ± 0.15, P = .009), whereas that of J0 did not (0.07 ± 0.04 vs 0.11 ± 0.09, P > .05). Furthermore, the amount of astigmatism, represented by the Pythagorean length of astigmatic components ( J0 and J45 ), increased significantly for 1 month postoperatively in the iris fixation group ( P = .049), but decreased to baseline level at 3 months and remained stable until 12 months ( P > .05; Figure 2 , Bottom left).


Interestingly, when the amount of refractive change was assessed, the iris fixation group showed significant hyperopic change from 1 week to 12 months (0.22 ± 0.16 diopter [D], P = .043), whereas the scleral fixation group was stable after surgery (0.06 ± 0.15 D, P > .05, Figure 2 , Bottom right).


Preoperative keratometric measurements using topography (Pentacam; Oculus, Wetzlar, Germany) showed mean astigmatism of 1.15 ± 0.11 D in the scleral fixation group and 1.24 ± 0.16 D in the iris fixation group, similar to postoperative measurements of 1.17 ± 0.10 D and 1.26 ± 0.16 D, respectively ( P > .05).


Operation Time


The operation time was significantly shorter in the iris than in the scleral fixation group (37.9 ± 8.5 min vs 51.6 ± 18.9 min, P = .0007).


Perioperative Complications


The frequency of perioperative complications, including intraocular bleeding, corneal endothelial cell loss, cystoid macular edema, and retinal detachment, was similar in the 2 groups ( Table 2 ). However, immediate postoperative inflammation 1 day after surgery was significantly more severe, as shown by mean grade of AC cells, in the iris than in the scleral fixation group (1.7 ± 8.7 vs 0.9 ± 1.1, P = .001). There were no between-group differences in grade of AC cells 1 week after surgery or in grade of AC flare during the entire follow-up period ( P > .05).


Jan 6, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Comparison of Clinical Outcomes of Iris Fixation and Scleral Fixation as Treatment for Intraocular Lens Dislocation
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