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Intraocular telescopic lens evaluation in patients with age-related macular degeneration

Alió, Jorge L MD, PhD*,a,b; Mulet, Emilia M MD, PhDa,b; Ruiz-Moreno, José Ma MD, PhDa,b; Sanchez, Maria José ODa,b; Galal, Ahmed MD, MSca,c

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Journal of Cataract & Refractive Surgery: June 2004 - Volume 30 - Issue 6 - p 1177-1189
doi: 10.1016/j.jcrs.2003.10.038
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Age-related macular degeneration (ARMD) is a leading cause of vision loss in older people, with rapidly increasing incidence in those over age 60 years.1 Recent improvements in managing patients with choroidal neovascularization using photodynamic therapy, transpupillary thermal therapy, photoablation, and submacular surgery offer opportunities for treatment but unfortunately are seldom followed by visual improvement. Once central vision has been lost, optical devices that increase the retinal image size through angular magnification of near and distant images offer a new alternative to improve visual function.2 Optical devices currently in use include high plus lenses and external telescopes, with the disadvantage of the very short focal length in the first case and a severely restricted visual field of 5 to 10 degrees. For these reasons, such low vision devices are functionally and cosmetically inadequate for many patients.3

Surgical alternatives such as the implantation of a high minus-powered intraocular lens (IOL) of −40 diopters (D) combined with external high-plus eyeglasses have also been suggested. Choyce4 first described the combination of an anterior chamber lens and positive spectacles in 1964. This combination with a posterior chamber IOL was then proposed by Donn and Koester.5 The disadvantage of this technique is the induction of extreme hyperopia up to +60 D, which is necessary to achieve a significant magnification. This causes a moderate to severe limitation of the peripheral visual field and achieves only moderate magnification that is highly sensitive to the distance between the eyeglass lens and the eye, so that any movement of the eye blurs the image.6

In 1997, Lipshitz and coauthors7 developed a miniature Gallilean telescope that functions intraocularly as a telesystem lens in conjunction with the dioptric powers of the cornea. This lens has been called an intraocular miniaturized telescope (IMT; Figure 1).

Figure 1.
Figure 1.:
(Alió) Intraocular miniaturized telescopic lens.

We report a multinational collaborative study aimed at reviewing visual outcome and complications following implantation of this 3.0× IMT in eyes with ARMD.

Patients and Methods

Intraocular Telescopic Lens Design

The IMT provides 3.0× magnification from a distance of 50 cm. The magnified image is projected onto a 20 degree central field of the retina. It enables natural eye movements and provides improved distance and near resolution.7 The IMT optics consist of an anterior plus lens and a posterior minus lens with a bubble of air between (Figure 2). The difference in the index of refraction of the lenses and the air increases the magnification power of the telescope. In the current design, all the components of the telescope are made of glass (anterior lens material: LaKN 14; posterior lens material: SF 11). In the plus lens, the radii of the anterior and posterior curvatures are 2.0547 and 18.1279, respectively; in the minus lens, the radii are 1.5228 and 2.22491, respectively (Figure 3).

Figure 2.
Figure 2.:
(Alió) Intraocular miniaturized telescopic lens components.
Figure 3.
Figure 3.:
(Alió) The lens system of the IMT.

Fixation of this device inside the eye is achieved by using poly(methyl methacrylate) loops to form the haptic plates, which are implanted in the capsular bag. Part of the implanted telescope protrudes through the center of the pupil after the surgery. Following implantation, the area of vision in confined within a 20-degree angle at the central visual field. The final required magnification can be achieved with plus eyeglasses. Given this condition, the final power of the IMT will be a multiple of the telescope and the added plus lenses.7

Patients

Forty eyes (40 patients) were included in this prospective multinational, protocolized study performed in 19 international centers (Table 1). The study protocol did not require ethical board committee approval and was performed following the tenets of the Helsinki Declaration.8 All the patients reviewed and signed a written consent. Inclusion and exclusion criteria for IMT implantation were determined by Vision Care Ophthalmic Technologies, manufacturer of the lens (Table 2).

Table 1
Table 1:
Investigator and patient data.
Table 1
Table 1:
(cont.)
Table 2
Table 2:
Inclusion and exclusion criteria for study.

Preoperative evaluation of the patients included bilateral complete slit-lamp biomicroscopy and tonometry, uncorrected visual acuity and best spectacle corrected visual acuity for distance and near with and without external telescope, specular microscopy, pachymetry, corneal topography, keratometry, axial length measurements, anterior chamber depth, fundus examination and fundus fluorescein angiography, and patient satisfaction report at the end of the study. The best corrected distance visual acuity (BCDVA) was measured by Snellen chart, and for near visual acuity Keeler A series held at 25 cm.

Surgical Procedure

Through a 3.2 mm limbal incision and large capsulorhexis (6.5 mm), a standard phacoemulsification procedure was performed, including polishing of the posterior capsule at the end of the procedure. The incision was enlarged to 10 mm, and the IMT was covered with a copious amount of ophthalmic viscosurgical devices (OVD) and then inserted into the eye with the lens loops carefully implanted at 6 and 12 o'clock positions inside the capsular bag. The OVD was then removed, and a peripheral iridectomy or iridotomy was performed. The pupil was constricted with intracameral acetylcholine, and the wound was sutured with 10-0 nylon sutures (Figure 4). The postoperative regimen included instillation of topical dexamethasone and tobramycin 0.3%, 4 times daily, tapered over 2 months.

Figure 4.
Figure 4.:
(Alió) Intraocular miniaturized telescopic lens implanted inside the bag.

The follow-up visits were at 1 day, 1 week, 1 month, 3 months, 6 months, and 1 year after surgery. During each visit, the patients were evaluated for visual acuity outcome for near and distance, endothelial cell count, cornea–IMT distance, and patient satisfaction. Rehabilitation was carried out in the low visual aid unit to train the patients to maximize the benefits of the IMT.

The cornea–IMT distance was evaluated clinically by slitlamp biomicroscopy. Endothelial cell count was measured in the cases operated on at the Instituto Oftalmológico de Alicante using Konan SP-5500 contact specular microscope preoperatively and 3 and 6 months and 1 year postoperatively. In these cases, a high-frequency ultrasound biomicroscopy (UBM) study was also performed to investigate the intraocular position of the IMT and potential damage to the intraocular structures (Paradigm, Zeiss). To test the possibility of an adequate angiographic study of the macula, standard digital fluorescein angiography procedures (Topcon Imaginet) were performed in 2 patients implanted at the Instituto Oftalmológico de Alicante.

The data concerning visual acuity measurements were obtained by transforming the decimal values into logMAR values. Visual acuity values were expressed in terms of mean ± SD for both logMAR and decimal values. Lines of visual acuity on the Early Treatment of Diabetic Retinopathy Study chart were made to facilitate the statistical analysis. Statistical analysis of the results was performed with the SPSS/8.0 for Windows. Statistically significant differences between data sample means were determined using Student t test after verification of data normality.

Results

Among 61 consecutive cases implanted with the IMT (21 women, 52.2%; 19 men, 42.5%), 40 patients were able to complete the study protocol up to 12 months of follow-up. The data concerning the 21 patients who were excluded from the study are given in Table 3. Patients' mean age was 77.1 years ± 5.9 (SD) (range 61 to 87 years).

Table 3
Table 3:
Data of patients excluded from the study.

Visual Acuity Outcomes

In Table 4, data for all the patients and their distance visual acuity outcomes for the operated and fellow eyes are given in decimal, Snellen, and logMAR values. Table 5 illustrates the mean values and changes of distance visual acuity in terms of improvement and loss, which is also addressed in Figure 5. Data regarding near visual acuity outcomes are shown in Table 6, which includes data for both operated and fellow eyes. Mean values and changes in near visual acuity are illustrated in Table 7 and Figure 6. Significant differences were found between preoperative and 1-, 6-, and 12-month postoperative values (paired sample t test, P = .001, P = .000, and P = .000, respectively). The difference between the near visual acuity pre- and postoperative values were significant at 6 and 12 months (paired sample t test, P = .004 and P = .01, respectively).

Table 4
Table 4:
Patient distance visual acuity data before (preop) and after (post) surgery.
Table 5
Table 5:
Postoperative change in distance visual acuity in the operated eye.
Figure 5.
Figure 5.:
(Alió) The change in the distance visual acuity.
Table 6
Table 6:
Patient near visual acuity data before (preop) and after (post) surgery.
Table 7
Table 7:
Postoperative change in near visual acuity in the operated eye.
Figure 6.
Figure 6.:
(Alió) The change in the near visual acuity.

At the end of the first year, mean uncorrected distance visual acuity (UCDVA) in the operated eye was 0.6 logMAR (0.25 ± 0.14, range 0.1 to 0.5 in decimal values) and 0.9 logMAR (0.125 ± 0.1, range 0.05 to 0.32 in decimal values) in the fellow eye. Although there was no statistically significant difference between operated and fellow eyes preoperatively (P = .02), these values were significant at 3, 6, and 12 months postoperatively (P = .009, P = .003, and P = .003, respectively).

At the end of the first year, the mean uncorrected near visual acuity (UCNVA) in the operated eye was 0.4 logMAR (0.4 ± 0.26, range 0.1 to 1.0 in decimal values) and in the fellow eye was 0.5 logMAR value (0.32 ± 0.22, range 0.1 to 0.7 in decimal values). There was no statistically significant difference between operated and fellow eyes preoperatively (P = .269); during the postoperative period, the differences between the operated and the fellow eyes were significant at 3 and 6 months (P = .09 and P = .011, respectively).

Corneal Endothelium–IMT Distance

Throughout the study, corneal endothelium–IMT distance was estimated by biomicroscopy; the mean value was not lower than 1.71 mm and the minimum absolute value, lower than 1.00 mm. There were no significant differences between intraoperative distance and the 1-, 6-, and 12-month postoperative measured distance; Figure 7 shows changes in the endothelium–IMT distance. There were no significant differences as calculated by paired samples t test (P = .13, P = .605 and P = .172, at 1, 6, and 12 months, respectively). This reflected the stability of the IMT inside the eye.

Figure 7.
Figure 7.:
(Alió) Graphic showing the change of the endothelia–intraocular telescopic lens distance through the period of the study. CI = confidence interval.

Corneal Endothelium Cell Study

Ten eyes were evaluated for endothelial cell density and loss. The mean preoperative endothelial cell count was 2930 ± 525 cells/mm2 (2100 to 3640); at the end of the study, it was 1928 ± 729 cells/mm2 (1129 to 2935). The difference between preoperative and postoperative values was of low significance (P = .058). The mean endothelium cell loss was 14.5% at 3 months, 30.8% at 6 months, and 34.5% at 12 months. Patients' endothelial cell count results showed stabilization around the end of the first year of the follow-up. There was no case of endothelial decompensation.

Intraocular Pressure Changes

The mean preoperative intraocular pressure (IOP) was 13.97 ± 3.1 mm Hg (range 8.0 to 21.0 mm Hg). Postoperatively, the mean IOP was 13.48 ± 3.1 mm Hg (range 10.0 to 22.0 mm Hg) at 1 month, 13.67 ± 3.5 mm Hg (range 10.0 to 26.0 mm Hg) at 3 months, 13.45 ± 2.75 mm Hg (range 10.0 to 19.0 mm Hg) at 6 months, and 13.92 ± 2.9 mm Hg (range 9.0 to 19.0 mm Hg) at 1 year. Throughout the follow-up period, there were no significant differences found between the preoperative IOP and the 1-, 6-, and 12-month postoperative IOP (Figure 8). The results showed insignificant differences as calculated by paired sample t test (P = .355, P = .056, and P = .011, respectively).

Figure 8.
Figure 8.:
(Alió) Graphic showing the change in intraocular pressure (IOP) throughout the study.

Position and Stability of the IMT

The position of the implanted IMT was evaluated immediately after implantation and then at 1 week, 3 months, 6 months, and 1 year. Immediately after implantation, 89% of the cases (37/40) showed the IMT fixated in the proper place inside the capsular bag. After 1 week, 87.5% of reported cases were in place (28/32); 93.75% (30/33) were in place at 3 months, and about 92% (34/37) were in place at 6 months and 1 year and did not change in the position, tilt, or decentration. To observe the behavior of the IMT inside the eye, UBM was performed on a number of the patients. Observing the relation of the different structures inside the eye and the IMT, the implanted IMT was found to be stable and to move with the movement of the globe (Figure 9, A). No mechanical trauma to the intraocular structures was observed during the UBM examination (Figure 9, B).

Figure 9.
Figure 9.:
(Alió) A: Ultrasound biomicroscopy picture showing intraocular telescopic lens implanted inside the eye. B: Ultrasound biomicroscopy picture showing the relation between the IMT and the corneal endothelium, corneal periphery, iris, and pupil.

Complications

Among the patients who completed the follow-up period (36/40), 14 eyes had adverse effects. In 3 eyes, explanted because of patient dissatisfaction and was implanted a conventional posterior chamber IOL. Two patients developed bubbles inside the IMTs, and these were replaced with a new IMT in 1 eye and a posterior chamber IOL in the other. One patient developed diplopia that required explantation and replacement of the IMT with a posterior chamber IOL. The rest of the adverse effects were managed during the postoperative period (Table 8). Complications in the postoperative follow-up period were classified as transient or persistent. Transient complications included corneal edema in 9 eyes (9/36, 25%), fibrin at the pupil in 12 eyes (12/36, 33.3%), synechias in 7 eyes (7/36, 19.44%), hyphema in 4 eyes (4/36, 11.11%), conjunctivitis in 2 eyes (2/36, 5.56%), uveitis in 3 eyes (3/36, 8.33%), and cyclitic membrane in 1 eye (1/36, 2.78%). Persistent complications included 1 eye with persistent pupillary cyclitic membrane (2.78%), persistent synechias in 2 eyes (5.56%), and posterior capsular opacification in 4 eyes (11.11%). Table 9 shows the visual outcomes of 5 of the 6 patients with complications during the postoperative period; 1 patient was lost to follow-up.

Table 8
Table 8:
Adverse effects and complications.
Table 9
Table 9:
Intraocular telescopic lens explantation data before (preop) and after (postop) surgery.

Only 4 patients developed posterior capsular opacification during the course of the study (Figure 10). Other parts of the capsule external to the IMT ridge showed the presence of Elschnig peals, which required no further treatment. Treatment with neodymium:YAG laser is possible in such cases, but the laser beam should be directed through the clear part of the haptic and not the glass optic of the IMT (Table 10).

Figure 10.
Figure 10.:
(Alió) Schematic diagram of an IMT lens implanted inside the capsular bag. The posterior part of the lens is pressing against the posterior capsule, decreasing the incidence of posterior capsule opacification.
Table 10
Table 10:
Summary of complications.

Fluorescein Angiography Study

In the 2 cases studied by conventional fluorescein angiography, adequate digital images were obtained of the macula (Figures 11, A and 11, B).

Figure 11.
Figure 11.:
(Alió) A: Fundus fluorescein angiography performed through the central part (optic) of the IMT after implantation. B: Another fundus fluorescein angiography of eye implanted with intraocular miniaturized telescopic lens.

Discussion

Patients with ARMD usually complain of distortion and disappearance of objects viewed directly, difficulty in reading small print, and difficulty recognizing faces. These complaints are the result of a loss of the central visual field.9,10 Rehabilitation with low-vision aids often allows these patients to continue performing many daily activities, including reading and watching television. Most of these visual aids use magnification to increase image size on the retina, limiting the patient's visual resolution. The gain in magnification at both distance and near is achieved at the expense of image resolution in the visual field and depth of focus. The disadvantages of these devices include short reading distance and distortion of images, as well as their weight and large size. Although newly developed devices such as head-mounted video-based image processing systems do not have the disadvantages of other systems, impractical handling remains a common explanation for why patients fail to use low-vision aids.11 Among the disadvantages of these new devices are high cost, restricted magnification, and the need for comprehensive, detailed training by a specialist.

The IMT is an implantable telescope that offers advantages over current options. The device is implanted in 1 eye to provide central vision, and the fellow eye continues to provide peripheral vision. Unlike an external telescope, there are no relative movements between the eye and the IMT. Natural eye movements move the telescope, which is fixated inside the eye (Figure 12).

Figure 12.
Figure 12.:
(Alió) Intraocular miniaturized telescope lens implanted in the bag 1 year postoperatively.

IMT implantation surgery is similar to ordinary phacoemulsification and IOL implantation. The incision has to be enlarged up to 10 mm, but astigmatism resulting from such a large incision can be corrected using external glasses and apparently does not influence the postoperative outcome.

In this report, we describe the visual outcome of 40 patients implanted with an IMT. Follow-up period was up to 1 year. Visual improvement was noted in the operated eye when comparing the preoperative and the 1-year postoperative distance visual acuity. Mean preoperative UCDVA was 0.9 logMAR (0.125 ± 0.01, range 0.1 to 0.3 in decimal values), and the 1-year postoperative UCDVA improved to 0.6 logMAR (0.25 ± .0.14, range 0.1 to 0.5 in decimal values).

Similar visual improvement was seen in the operated eyes at 1 year for near visual outcome. Mean preoperative UCNVA was 0.8 logMAR (0.16 ± 0.13, range 0.1 to 0.5 in decimal values), and the 1-year postoperative UCNVA was 0.4 logMAR (0.4 ± .0.26, range 0.1 to 1.0 in decimal values). At 1 month following surgery, all the patients included in the study had a mean UCDVA improvement of 2 lines in the operated compared with the fellow eye, which had a mean deterioration of 1.1 lines on the ETDRS visual chart. At 6 months all the patients had a mean UCDVA improvement of 3.5 lines in the operated eye compared with the fellow eye, which had a mean deterioration added to the previous deterioration of 0.1 lines. At the end of the study, the mean improvement reported for UCDVA was 3.5 lines, and the mean deterioration of the fellow eye was 1.1 lines.

The stability of the IMT in the implanted eye was confirmed by this study. Only inadequate placement of the lens during surgery caused decentration with loss of the optical advantages of the IMT, and this was the explanation in all cases of tilting caused by decentration. Immediately following implantation, 33 IMTs in 40 eyes were implanted inside the capsular bag, 1 was fixated at the sulcus, 1 was unstable, and 1 was tilted; data for 3 patients were not available. At 1 week postoperatively, 28 IMTs of 40 eyes were implanted inside the capsular bag, 1 was fixated at the sulcus, 1 was tilted, and 2 were decentered; data for 8 patients were not available. Three months postoperatively, 30 IMTs were implanted inside the capsular bag, 1 was fixated at the sulcus, 1 was tilted, and 2 were decentered; data for 6 patients were not available. Six months postoperatively, 34 IMTs were implanted inside the capsular bag, 1 was fixated at the sulcus, 1 was tilted, and 2 were decentered.

Following implantation of the IMT, corneal endothelium–IMT distance was found to be stable. A significant endothelial cell loss was found in this study, probably related to the surgical procedure. Despite this, no single case developed corneal decompensation. Few complications developed during the course of the study. Seven eyes (17.5%) developed persistent complications in the form of PCO (4 eyes, 10%), synechias (2 eyes, 5%), and fibrin deposition on the pupil (1 eye, 2.5%). Major complications including corneal decompensation, glaucoma, iris atrophy, vitreous hemorrhage, retinal detachment, posterior dislocation of the telescope, and IMT malpositioning did not occur.

Postoperative follow-up of the posterior segment state was somewhat difficult because the implanted telescope did not permit detailed fundus examination. The evaluation of ARMD was difficult, as was evaluation for possible postoperative posterior segment complications of cataract surgery, such as cystoid macular edema. We demonstrated, however, that a standard fluorescein angiography examination can be performed successfully through the IMT optic, a finding that may be relevant for the future clinical use of these intraocular devices.

Six patients (6/40, 15%) were explanted throughout the first year of the follow-up, and the IMT was replaced by either another IMT or a posterior chamber IOL. The main causes of IMT explantation were the development of bubbles inside the IMT because of failure of the IMT manufacturer's safety precautions and patient dissatisfaction because of inadequate visual outcome (Figure 13). Improvements in lens manufacture and more adequate patient selection criteria will decrease future incidence of such complications.

Figure 13.
Figure 13.:
(Alió) Postoperative appearance of the IMT.

Implantation of IMTs did not resolve some of the important problems of the external telescopes regarding field of vision and postoperative rehabilitation. All patients had narrowing of the field of vision, and postoperative low-vision rehabilitation was difficult for most patients.

This report confirms the potential of IMT technology for the visual rehabilitation of patients affected by ARMD. Our visual results agree with preliminary reports12 in a small series of patients who are also included in this report. The main difficulties found in the use of this technology are the strict patient selection criteria required to avoid quick evaluative forms of ARMD and the need to choose eyes with a potential for visual rehabilitation. Cases with very low levels of residual vision seem to be poor candidates for IMT implantation. Adequate postoperative visual rehabilitation is also mandatory and should be performed by trained low-vision specialists. Intraocular miniaturized telescopic lens-related surgical complications were few and will probably diminish in the future as surgical techniques and instrumentation improve. The promising results of this study show that IMT may play an important role in the future visual rehabilitation of selected cases of ARMD.

References

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© 2004 by Lippincott Williams & Wilkins, Inc.