Volume 34, Issue 1 , Pages 87-94, January 2008
Mirror telescopic intraocular lens for age-related macular degeneration:
Design and preliminary clinical results of the Lipshitz macular implant
Article Outline
Purpose
To conduct a pilot study evaluating the visual and surgical outcomes of an intraocular mirror telescopic intraocular lens, the Lipshitz macular implant (LMI) (Optolight Vision Technology), for age-related macular degeneration (ARMD) and other macular pathology.
Setting
Dr. Agarwal's Eye Hospital and Eye Research Centre, Chennai, India.
Methods
The LMI was implanted in patients with bilateral macular pathology and visual acuity worse than 20/200 in whom vision improved with a ×2.5 external telescope preoperatively. The LMI was implanted after conventional phacoemulsification or microphakonit. The minimum follow-up was 6 months.
Results
Six eyes of 6 patients had surgery in the worse eye. Four eyes had ARMD, and 1 eye each had myopic macular degeneration or macular dystrophy. There were no intraoperative complications. The mean gain in distance acuity was 3.66 lines ± 1.88 (SD), and the mean increase in the Early Treatment Diabetic Retinopathy Study score for near acuity was 50.83 ± 9.15 logMAR. The best corrected distance acuity and near acuity improved significantly (both P = .014). The mean change in endothelial count was −5.79% ± −4.07%. The mean postoperative corneal endothelial–LMI distance was 3.15 ± 0.31 mm. A good central fundus view was possible around the mirrors in all eyes. Fundus fluorescein angiography showed good visibility of the retina up to the midperiphery. The mean score on a quality-of-life questionnaire was 11.16 ± 1.72 (SD) preoperatively and 4.50 ± 0.83 postoperatively, a statistically significant improvement (P = .014).
Conclusions
The LMI may be an effective solution for optical rehabilitation of patients with ARMD or other macular pathology by increasing the central image on the retina while preserving peripheral vision. The surgery and visual recovery were quick, and the improvement in quality of life was significant.
Macular pathology causes a significant amount of morbidity worldwide and thus has a large impact on public health.1, 2 Age-related macular degeneration (ARMD) is the leading cause of legal blindness in the industrial world. Age-related macular degeneration has been divided into dry or non-exudative and wet or exudative types. Until now, not much attention has been focused on visual rehabilitation of patients with ARMD using optical principles. A prosthetic device for ARMD, the implantable miniature telescope (IMT), was tested.3 The drawbacks included loss of peripheral vision in the operated eye, difficult surgical technique, endothelial compromise, difficulty in retinal visibility, difficulty in future retinal laser treatments,4 difficulty due to the size and weight of the implant, aniseikonia due to the disparity of images between the 2 eyes, and the need for prolonged visual rehabilitation training.
To solve these problems, one of us (I.L.) designed a new intraocular lens (IOL), the Lipshitz macular implant (LMI) (Optolight Vision Technology), that magnifies the image on the retina using a mirror telescope. In this paper, we describe the LMI and report the findings in a pilot study of its use in patients with dry or wet ARMD or with other diseases that affect the macula and thus central vision. This was the first experimental trial of the LMI.
Patients and methods
Macular Implant Design
The LMI is a conventional IOL that incorporates 2 miniature mirrors in the Cassegrain telescopic configuration. The mirrors modify the reflected image on the retina (Figure 1, A and B). The IOL is simple to manufacture and has a dual optical system in which light passing through the center of the optic is magnified by the Cassegrain telescope and peripheral light passes through the normal IOL configuration. The overall diameter of the IOL is 13.0 mm, and the optic is 6.5 mm. The anterior central mirror is 1.4 mm. The posterior mirror, which is doughnut shaped and 2.8 mm in diameter, has a central clear area of 1.4 mm in diameter. The peripheral zone of the optic is similar to that of a normal IOL to provide undisturbed peripheral vision. The reflecting surfaces of the LMI are coated with multiple layers of titanium oxide and silicon dioxide (dielectric coatings), which creates a mirror effect. The mirrors are 1 to 2 μm thick. The entire IOL is coated with poly-para-xylylenes (Parylene C) to enhance biocompatibility.
Figure 1
A: The LMI mirror telescopic IOL. B: Illustration depicting how the LMI functions. C: The LMI magnifies the central image on the retina. D: Gray trace of light demonstrating the magnification caused by the mirrors.
This LMI was designed to have ×2.5 magnification; that is, it magnifies the central image on the retina 2.5 times (Figure 1, C and D). The patient thus sees a magnified central image through the mirror telescope and a normal nonmagnified image through the periphery of the IOL. This provides magnified central vision while maintaining orientation in space due to normal peripheral vision (Figure 2, Figure 3). All testing was done before the pilot study was performed in a laboratory while the IOL was being prepared (Figure 4).
Figure 2
Schematic representation of LMI showing dimensions.
Figure 3
Diagram of the magnified central image and normal peripheral image.
Figure 4
Laboratory studies performed in designing the LMI.
Study Design
A prospective nonrandomized pilot feasibility clinical trial was conducted at Dr. Agarwal's Eye Hospital and Eye Research Centre from June to December 2006. Patients with bilateral macular pathology, with distance or near visual acuity less than 20/200, cataract with an NS grade less than 2, and no other ocular or systemic disease in whom vision improved when tested with a ×2.5 external telescope preoperatively were selected. All patients provided informed consent after receiving an explanation of the potential benefits and possible complications of the procedure. Patients' motivations, communication skills, and availability for 6 months of follow-up were considered before their inclusion in the study.
Preoperative Assessment
Preoperatively, all the patients had a detailed examination including best corrected visual acuity (BCVA) for near and distance with and without an external telescope, slitlamp examination, tonometry, pachymetry, specular microscopy, fundus examination, and fundus fluorescein angiography. The BCVA was measured with a Snellen chart and near vision, using the Early Treatment Diabetic Retinopathy Study (ETDRS) near vision chart at 20 cm.
Surgical Technique
All surgeries were performed by the same surgeon (Am.A.). Conventional coaxial phacoemulsification or 0.7 mm microphakonit5 was performed (Figure 5, A and B). At the end of surgery, the corneal tunnel was increased to 6.5 mm with a diamond knife or regular keratome and the LMI was placed in the capsular bag. In the 1 patient who was pseudophakic, the LMI was implanted after the existing IOL was explanted (Figure 5, C and D). All patients were placed on a routine postoperative regimen of a topical antibiotic–steroid combination for 6 weeks.
Figure 5
A: Microphakonit cataract surgery (0.7 mm) is performed. B: The LMI is implanted after the cataract is removed. C: A posterior chamber IOL is being explanted in a pseudophakic eye with ARMD. D: The LMI is implanted after the IOL is explanted.
Postoperative Assessment
Follow-up visits were at 1 day, 1 week, and 1 and 6 months. Slitlamp examination, noncontact tonometry, anterior segment optical coherence tomography (AS-OCT), specular microscopy, and fundus evaluation were performed at each visit. The near and distance BCVAs were also measured at all visits. Fundus evaluation of all patients was done by the same retinal specialist (M.L.) to grade the difficulty of the fundus examination with indirect ophthalmoscopy and to assess the possibility of future retinal photocoagulation for peripheral retinal pathology. The grading used was as follows: 0 = no difficulty seeing up to the ora serrata; 1 = difficulty seeing the ora serrata due to glare; 2 = view possible up to the midperiphery; 3 = view possible only up to the equator; 4 = only the central fundus (ie, disc and macula) visible.
Visual acuity measurements were transformed from Snellen values into logMAR equivalents. Lines of improvement in visual acuity were determined using a visual acuity conversion chart.
At 6 months, patients were given a quality-of-life questionnaire6 (Figure 6) on which they were asked to evaluate activities of daily living and their satisfaction. The questionnaire was designed as a general assessment.
Figure 6
Quality-of-life questionnaire.
Statistical Analysis
Statistical analysis of the results was performed with SPSS for Windows (version 8.0, SPSS, Inc). Statistically significant differences between mean values were determined using the Friedman test after data normality was verified.
Results
Six eyes of 6 patients had surgery for implantation of the LMI in the worse eye. Four eyes had ARMD, and 1 eye each had myopic macular degeneration or macular dystrophy. There were five men (83.33%) and 1 woman (16.67%). There were no intraoperative complications in any case, and all 6 patients completed the entire follow-up.
Table 1 shows the changes in distance and near visual acuities between preoperatively and 1 month and 6 months postoperatively as well as the gain or loss of lines in the operated eyes and fellow eyes. Distance visual acuity improved for up to 6 months postoperatively. Two patients had lost lines in the operated eye by 1 week postoperatively; 1 patient had an improvement after 1 month and the other, at 6 months. The first patient lost lines as a result of slight postoperative inflammatory reaction, and the second patient had postoperative cystoid macular edema that spontaneously resolved. At the end of 6 months, no patient had a decrease in distance visual acuity from preoperative levels and the improvement in distance BCVA and near BCVA was statistically significant (P = .014 and P = .014, respectively; Friedman test).
Table 1. Changes in distance and near visual acuities in operated and fellow eyes.
| Distance Acuity (LogMAR) | Near Acuity (ETDRS Score, LogMAR) | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Preop | 1 Mo Postop | 6 Mo Postop | Lines Gained or Lost | Preop | 1 Mo Postop | 6 Mo Postop | Change in Score | |||||||||
| Case | OE | FE | OE | FE | OE | FE | OE | FE | OE | FE | OE | FE | OE | FE | OE | FE |
| 1 | 0.60 | 0.60 | 0.78 | 0.60 | 0.48 | 0.60 | +1.5 | 0 | 37 | 55 | 77 | 55 | 87 | 37 | 50 | −18 |
| 2 | 2.00 | 0.60 | 0.80 | 0.60 | 1.00 | 0.78 | +6.0 | −1.5 | 7 | 67 | 55 | 67 | 55 | 67 | 48 | 0 |
| 3 | 1.30 | 1.00 | 1.00 | 1.00 | 1.00 | 1.18 | +3.0 | −1.5 | 7 | 37 | 67 | 37 | 72 | 37 | 65 | 0 |
| 4 | 1.45 | 0.78 | 1.00 | 1.00 | 1.00 | 1.18 | +2.5 | −4.0 | 37 | 87 | 77 | 77 | 87 | 67 | 50 | −20 |
| 5 | 1.45 | 1.30 | 1.18 | 1.30 | 1.18 | 1.45 | +3.0 | −1.5 | 35 | 82 | 67 | 82 | 72 | 72 | 37 | −10 |
| 6 | 2.00 | 2.00 | 1.00 | 2.00 | 1.00 | 2.00 | +6.0 | 0 | 22 | 55 | 67 | 55 | 77 | 52 | 55 | 0 |
| Mean | 1.47 | 1.05 | 0.96 | 1.08 | 0.94 | 1.20 | 3.66 | −1.41 | 24.16 | 63.83 | 68.33 | 62.16 | 75.00 | 55.33 | 50.83 | −8.00 |
| SD | 0.52 | 0.54 | 0.15 | 0.52 | 0.24 | 0.50 | 1.88 | 1.46 | 14.42 | 18.72 | 8.16 | 16.57 | 11.91 | 15.70 | 9.15 | 9.38 |
Table 2 shows the changes in the endothelial cell counts over time. The mean endothelial cell count in the operated eyes was 3018.33 cells/mm2 ± 513.09 (SD) preoperatively and 2842.66 ± 593.01 cells/mm2 at 6 months. The mean change in the operated eye was −5.79% ± −4.07%. All the eyes had an anterior chamber depth within the normal range. Analysis of AS-OCT (Figure 7) showed the LMI was well positioned and the anterior chamber dimensions were normal in all eyes. The mean postoperative corneal endothelial–LMI distance was 3.15 ± 0.31 mm.
Table 2. Changes in the endothelial cell count in operated eyes.
| Endothelial Cell Count (cells/mm2) | |||
|---|---|---|---|
| Case | Preop | Postop | % Change |
| 1 | 2462 | 2185 | −11.25 |
| 2 | 3107 | 3014 | −2.99 |
| 3 | 2340 | 2072 | −11.45 |
| 4 | 3201 | 2976 | −7.03 |
| 5 | 3644 | 3568 | −2.09 |
| 6 | 3356 | 3241 | −3.43 |
Figure 7
Anterior segment OCT showing adequate space between the cornea and LMI.
The difficulty of the fundus evaluation was grade 1 in all quadrants. A good central fundus view was possible around the mirrors in all patients. Fundus photographs taken from the center of the lens had reflections from the posterior mirror (Figure 8, A). Although the reflections blocked visibility up to half the view, photographs taken from the periphery of the optic after complete pupil dilation had satisfactory retinal views (Figure 8, B). Fundus fluorescein angiography showed good visibility of the retina up to the midperiphery (Figure 8, C). Reflexes from the mirror component of the IOL were seen when a light was shined on the patient's face (Figure 9, Figure 10).
Figure 8
A: Fundus photographs from the center of the lens have reflections from the posterior mirror. B: Photographs taken from the periphery of the optic after complete dilatation of the pupil show satisfactory retinal view. C: Fundus fluorescein angiography show good visibility of the retina up to the midperiphery.
Figure 9
Slitlamp view of the LMI.
Figure 10
Postoperative external photograph showing mirror reflexes.
Results of the quality-of-life questionnaire showed that the ability to read large print, count money, and move independently was improved after surgery in most patients. The ability to read watches or clocks, dial the telephone, and use a computer keyboard improved moderately in most patients, and the ability to read small print improved slightly in most patients. The mean quality-of-life score was 11.16 ± 1.72 preoperatively and 4.5 ± 0.83 postoperatively, a statistically significant improvement (P = .014). All patients reported slight glare, especially in bright sunlight and while driving at night due to headlights of oncoming vehicles. Two patients also reported shadowing of images that occluded the unoperated eye; both patients adapted within 3 months of surgery and did not have further complaints of shadowing.
Discussion
Patients with ARMD usually have difficulty reading as well as seeing near objects (eg, unable to clearly recognize faces). Other macular pathologies cause similar difficulties with varying degrees of severity. Optical modalities to improve the size of the image on the central retina in these patients (eg, low-vision aid loupes, magnifiers) are used at the expense of loss of field of vision and depth of focus. A short reading distance, image distortion, the weight and large size of the aids, and poor cosmesis are other problems associated with these modalities. Although relatively new devices, such as head-mounted video-based image-processing systems, are available, patients report problems handling them, a common cause of failure of low-vision aids.7
The Lipshitz IMT met with limited success. The newer LMI is the equivalent of 2 IOLs and is well supported by placement within the capsular bag alone. Although there were no cases of posterior capsule rupture in our series, the LMI can also be placed in the sulcus with optic capture (to ensure centration) in eyes with a posterior capsule rupture.
The LMI is similar to the IOLs used after phacoemulsification and is placed entirely in the capsular bag in a similar way. It requires the corneal incision to be enlarged to only 6.5 mm rather than the 10.0 mm the IMT requires, thus reducing surgically induced astigmatism. The mean change in endothelial count in the operated eye was −5.79% ± −4.07% cells/mm2, which is comparable to values in other studies of phacoemulsification.8, 9
The field of view with the IMT is limited and is confined to a narrow 20-degree angle at the central visual field.10, 11 The operated eye is used for central magnified vision, and the contralateral unoperated eye is used for peripheral vision. Thus, bilateral IMT implantation is not possible. Bilateral LMI implantation is possible as the device provides enlarged central and normal peripheral vision. Kaskaloğlu et al.10 found that despite an improvement in distance and near acuity postoperatively in patients with an IMT, the improvement did not translate into an increase in patients' ability to perform activities of daily living. In contrast, based on the questionnaire, the LMI led to a significant improvement in our patients' quality of life. The postoperative visual rehabilitation of patients with IMT is often prolonged and difficult and requires the services of trained low-vision aid specialists. In addition, successful treatment requires greater patient motivation to complete the rehabilitation process. These factors make this treatment challenging despite anatomical and surgical success.10, 11 In contrast, patients with an LMI can function normally and see the enlarged image starting in the immediate postoperative period.
Two of our patients reported shadowing of images that occluded the unoperated eye; the cause might have been overlapping of the magnified central image through the mirror telescope and a normal central nonmagnified image through the periphery of the IOL. Both patients adapted within 3 months of surgery, after which they did not have complaints of shadowing. This was probably the result of natural brain adaptation and of the patients learning to ignore the shadowing.
The IMT is also associated with problems in the detailed visualization of the fundus, which makes evaluation of the ARMD difficult.10, 11 To a great extent, the LMI overcomes these problems, although slight glare was present on fundoscopy in our study. The mirror reflexes on shining external light onto the eye was not of major concern to our patients but might be a problem in younger patients more concerned with cosmesis. Most patients, however, did not mind the reflexes as they perceived the LMI to be a significant improvement over wearing cumbersome, cosmetically unappealing low-vision aids.
The LMI provides magnified central images up to 2.5 times the normal while maintaining the normal peripheral vision through the peripheral portion of the lens, unlike the IMT.11 Because of this, the LMI can be implanted in both eyes of a patient. Furthermore, if there is further macular deterioration, increased magnification can be achieved by adding plus eyeglasses up to +4.00 diopter. There is no relative movement between the eyes and the LMI, unlike with an external telescope.
In conclusion, the LMI, a mirror telescopic IOL, provides optical rehabilitation of patients with ARMD or other macular pathology by increasing the central image on the retina while preserving peripheral vision. The device can be used not only in patients with dry or wet ARMD but also in those with retinitis pigmentosa, diabetic maculopathy, Stargardt disease, macular holes, glaucoma, solar retinitis, Usher syndrome, toxoplasmosis, macular degeneration that is not age related, other inflammatory macular disease, albinism, or myopic macular degeneration. The LMI can be implanted bilaterally, unlike the IMT.
The surgical technique, including LMI implantation, was relatively simple to perform. No significant endothelial loss was noted, probably because the surgery is similar to conventional procedures for IOL implantation after phacoemulsification and the LMI is smaller than the IMT. The patients were comfortable in the postoperative period. The surgery and visual recovery were quick, and patients had a significant improvement in their quality of life. The postoperative examinations were easy, with minimal glare due to reflections from the mirrors; the glare did not appear severe enough to cause difficulty in case of future retinal photocoagulation.
References
- . Prevalence of age-related macular degeneration in the United States. Arch Ophthalmol. 2004;122:564–572
- . Potential public health impact of age-related eye disease study results; AREDS report no. 11. Arch Ophthalmol. 2003;121:1621–1624
- . An intraocular telescopic lens for macular degeneration. Ophthalmic Surg Lasers. 1997;28:513–517
- . Feasibility and safety of laser treatments in eyes with an intraocular implantable miniature telescope. J Cataract Refract Surg. 2003;29:1005–1010
- . Consultation section: cataract surgical problems. J Cataract Refract Surg. 2007;33:183–185
- . Visual Function Index (VF-14) in exudative age-related macular degeneration of long duration. Am J Ophthalmol. 2003;135:206–212
- . Nutzungshäufigkeit vergrößernder Sehhilfen im Wohnbereich von Sehbehinderten. [Home use frequency of low-vision aids by partially sighted]. Klin Monatsbl Augenheilkd. 1999;215:305–310
- Endothelial cell loss after phacoemulsification: relation to preoperative and intraoperative parameters. J Cataract Refract Surg. 2000;26:727–732
- Endothelzellverlust nach Phakoemulsifikation und 3,5 vs. 5 mm Hornhauttunnelinzision. [Endothelial cell loss after phacoemulsification and 3.5 vs. 5 mm corneal tunnel incision.]. Ophthalmologe. 1995;92:476–483
- . Medium-term results of implantable miniaturized telescopes in eyes with age-related macular degeneration. J Cataract Refract Surg. 2001;27:1751–1755
- Intraocular telescopic lens evaluation in patients with age-related macular degeneration. J Cataract Refract Surg. 2004;30:1177–1189
First author:
Amar Agarwal, MS, FRCS, FRCOphth
Dr. Agarwal's Eye Hospital and Eye Research Centre, Chennai, India
Dr. Lipshitz holds the patents for the mirror telescopic lens as well as shares in Optolight Vision Technology, the manufacturer of the Lipshitz macular implant. No other author has a financial or proprietary interest in any material or method mentioned.
PII: S0886-3350(07)01768-3
doi:10.1016/j.jcrs.2007.08.031
© 2008 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.
Volume 34, Issue 1 , Pages 87-94, January 2008
