Enhancing the Functional Performance of Patients with Late-Stage Age-Related Macular Degeneration Implanted with a Miniature Telescope using Rehabilitation Training

This was a retrospective study conducted between February 2022 to June 2023 at the Policlinico Gemelli hospital in Rome which included participants with bilateral end-stage AMD. Informed consent to participate in the study was obtained from all participants. The study was performed according to the guidelines of Declaration of Helsinki and approved by the Ethics Committee of Policlinico Gemelli hospital (approval code: 4634).

The screening process was performed by a staff composed of low-vision specialists and orthoptists. Patients were screened based on both non-clinical criteria (including realistic expectations, supportive family, familiarity with available low-vision devices) and medical history with no existing cognitive or communication problems, which represent important parameters correlated with improved health outcomes [25]. Moreover, patients were informed that the functional visual output from the implant would be a new type of functional vision rather than restoration of previous vision and will require a considerable investment in terms of effort and time. Inclusion criteria included cataract and bilateral geographic atrophy or disciform scar, ≥ 55 age, good peripheral vision, bilateral BCDVA comprised between 20/80 and 20/800 (0.6–1.6 logMAR), anterior chamber depth (ACD) ≥ 2.5 mm, endothelial cell density (ECD) ≥ 1600 cells/mm². Moreover, the eye selected for the study needed to demonstrate a minimum improvement of five letters on the Early Treatment Diabetic Retinopathy Study Charts (ETDRS) scale through the use of an external telescope simulator (ETS 3.0X-FF; VisionCare Ophthalmic Technologies Ltd., Petah Tikva, Israel) before undergoing surgery. Patients who had active choroidal neovascularization (CNV) or had received CNV treatment in the preceding 6 months, a history of intraocular or corneal surgery, corneal stromal or endothelial dystrophies (including guttae), myopia exceeding 6.0 D, hyperopia exceeding 4.0 D, a record of steroid-induced increases in intraocular pressure (IOP), preoperative IOP of 22 mmHg or higher while on maximum medication, or uncontrolled glaucoma in the study eye were not included in the study. Individuals with ophthalmic conditions that could compromise peripheral vision in the fellow eye were also excluded. Lastly, patients exhibiting significant cognitive impairment evaluated according our clinical practice, potentially affecting their ability to comprehend instructions, follow guidelines, or participate in appropriate visual training or rehabilitation with the implant, were also excluded from the study. If both eyes were eligible for implantation, the dominant or preferred eye by the patient was selected for implantation.

All surgeries were performed at the Policlinico Gemelli hospital by SR, AS, and TC using a previously published procedure [16]. Patients were anesthetized using sub-tenon block 10 min before surgery. A sclerocorneal incision of 8.0 mm was created at the 12 o’clock position, and then continuous manual circular anterior capsulorhexis with a diameter of at least 6.0 mm was carried out, and standard phacoemulsification was performed. SING IMT was inserted into the anterior chamber by means of a preloaded delivery system and positioned into the capsular bag with two haptics inferiorly and one superiorly. Then, the sclerocorneal incision was sutured using five single 10–0 monofilament nylon sutures. Finally, an iridectomy was performed at 12 o’clock position. Following surgery, patients received topical therapy with antibiotic and anti-inflammatory drops for 1 month and cycloplegic drops for 2 weeks (the iris was dilated during this period).

SING IMT is based on bi-ocular alternating vision. To optimize functional performance, a greater collaboration of the two eyes is required to autonomously exclude the image according to the patient’s visual needs. To do so, a rehabilitation training program was set up based on the expertise of the ophthalmologists, surgeons, and orthoptists of the Policlinico Gemelli Hospital. Prior to the program, a patient survey was conducted to understand the activities needed with the following results: reading (36%), writing (21%), watching TV (29%), and face recognition (14%). The program started after the dilation drop regimen at 6 weeks after surgery because the healing process and dilation could interfere with clear vision. It covered five different key skills including (1) visual abilities, (2) reading, (3) writing, (4) visual motor integration, and (5) mobility (Fig. 1). Training of each skill consisted of at least seven sessions for 1 h and a half each (with a 15-min break) every 2 weeks over a period of 6 months. For the reading training protocol, a series of exercises designed for macular degeneration (as ocular-manual coordination, ocular motility, number to number, fovea centration, identifying the center of a spot, image differences, identifying differences between two images) was performed in this study to improve the reading skills of patients. Lights and high-contrast shapes were used during the sessions. To improve reading skills, the patient needed to train the PRL in the implanted eye to be able to read progressively smaller letters, words, sentences, and numbers. Depending on the corneal astigmatism and presence of suture, prescription glasses were used for some patients during the reading training protocol. The full protocol for each skill is described in Supplementary Material #1.

Baseline characteristics (including BCDVA, axial length, and anterior chamber depth) were collected from medical records. Functional outcomes (including reading acuity, reading speed, and fixation stability) were then measured after rehabilitation sessions conducted at 6, 8, 10, 12, 14, 16, and 24 weeks after SING IMT implantation.

BCDVA was assessed using the ETDRS charts. Slit-lamp anterior segment and fundus examination, followed by optical coherence tomography (OCT) was also performed (Optovue Solix Fullrange OCT). Axial length (AL) and anterior chamber depth (ACD) were evaluated using optical biometry (ZEISS IOLMaster® 500). Corneal endothelial cell density (ECD) was measured with specular microscopy (CSO Endothelial Microscope Perseus).

Reading acuity (RA) in LogMAR was evaluated monocularly with the Minnesota Reading (MNRead) test charts at 25 cm adding + 4 D spherical to the distance refractive correction.

Reading speed (RS) was evaluated monocularly by counting the number of words read in 1 min on the International Reading Speed Texts (IREST) charts that allowed patients to read fluently, without making errors, the 0.6 M (5.9-character print) on MNRead charts.

Fixation stability (FS) was evaluated in seconds and measured the time to maintain the image with the implanted eye to view static objects at the distance of 4 m; the fellow eye was occluded, after the identification of the PRL (as object identification). Microperimetry was not technically possible due to the implant optical characteristics. Fifteen seconds was considered as a normal fixation stability as reported in the literature [26].

BCDVA was evaluated with the ETDRS and was expressed in letter score values at 3 m with the best refractive correction.

All functional and visual outcomes were reported as mean ± standard deviation and paired t tests were used to compare them at baseline and different postoperative timepoints. All analyses were performed using GraphPad Prism 6 (GraphPad, San Diego, CA, USA).

In total, 11 patients implanted with the SING IMT between February and June 2022 were included in this retrospective study. Baseline demographics and clinical characteristics of these patients are detailed in Table 1. All patients were white and presented geographic atrophy in both eyes. Most of the patients were male (72.7%, n = 8) and the mean age was 77.5 ± 8.0 years. SING IMT were monocularly implanted in the right eye in 63.6% of the patients. The baseline BCDVA (in letter score) was 12.5 ± 8.6, which corresponds approximatively to 1.45 LogMAR or 20/600 Snellen. No patient was lost for follow-up during this study.

After the first session of the rehabilitation program (6 weeks postoperatively), mean RA was 0.64 ± 0.26 LogMar (Fig. 2A). After the last session (24 weeks postoperatively), mean RA was 0.45 ± 0.19 LogMAR. This improvement of ~ 0.2 LogMar was found statistically different (p = 0.0181) from first session to last session. The maximum RA of each patient was achieved after four sessions of the rehabilitation program for most of the patients (55%, n = 6). (Fig. 2B).

Similar to RA, mean RS improved from the second program session (16.9 ± 11.4 words per minute) to the last session (30.9 ± 17.6 words per minute) (p = 0.0057 between the first and the second to last session, however the p value not calculable between the first and the last session due to the lost to follow-up) (Fig. 3A). The maximum RS of each patient was achieved after five sessions of the rehabilitation program for most of the patients (64%, n = 7) (Fig. 3B).

The rehabilitation program was also shown to improve the fixation stability of patients after SING IMT implantation (Fig. 4). Most of the patients (55%, n = 6) required only two sessions to achieve 15 s or more of fixation stability. All patients achieved a fixation stability of at least 15 s after the last rehabilitation session.

From baseline to the last follow-up visit, 82% of patients (n = 9) achieved an improvement of ten letters, 54.5% (n = 6) an improvement of 15 letters, and one patient an improvement of 25 letters (Fig. 5). At 24 weeks after SING IMT implantation, mean BCDVA was 28.5 ± 7.4 letter score which was significantly higher than baseline BCDVA (p < 0.0001). Moreover, BCDVA was found to be significantly improved between the first and the last rehabilitation sessions (p = 0.0125).