Visual Outcomes in Delayed Ophthalmic Procedures After Early and Prolonged Childhood Blindness in Adults

1. Introduction

In 1688, Irish philosopher William Molyneux (1656–1698) asked his colleague, English physician and philosopher John Locke (1632–1704), a question which has stimulated multi-disciplinary scholarly work ever since. Molyneux asked whether a congenitally blind man suddenly obtaining eyesight would be able to visually distinguish a cube from a sphere if he had previously been familiar with these shapes using his sense of touch [1]. Since then, congenital cataract surgery has been the predominant clinical approach towards answering Molyneux’s question. Nonetheless, cataract surgery poses certain limitations in this regard. In some instances, surgery can rapidly restore vision in cataracts which are assumed to be congenital, but deeper investigation cannot establish that the cataracts were truly congenital.

Existing studies have examined visual outcomes in delayed ophthalmic procedures, primarily in the pediatric population. For example, delayed surgery for a young child with congenital cataracts may result in irreversible visual impairment due to amblyopia [2]. In a prospective study conducted in India, investigators reported that children who had late treatment of early-onset dense cataracts experienced significant visual improvement [3]. These children all presented with cataracts within 6 months of birth and underwent treatment at 8 years of age or older. Mean logMAR acuity for best corrected visual acuity (BCVA) at distance was 2.19 preoperatively (Snellen: 20/2000) and improved to 1.32 postoperatively (Snellen: 20/250). Similarly, a retrospective multicenter review of shorter delays in treatment of congenital cataracts reported that children whose surgery was delayed past 10 weeks of age had generally worse visual outcomes compared to children whose surgery was performed sooner [4]. For example, among infants who had surgeries delayed past 10 weeks of age, BCVA was never better than 20/100.

These previous findings highlight that delayed ophthalmic management in amblyopic-age children can improve visual outcomes, although perhaps not as well as treatment performed more quickly. While congenital cataracts generally are addressed urgently, during a longer period in early childhood, up through at least age 7 years, the brain circuitry is plastic, and the visual system continues to develop [5]. The critical period refers to the peak window in which deprivation, strabismus, or anisometropia may result in permanent visual impairment, leading to amblyopia [6]. During this period, children respond best to treatment with patching or atropine drops, and past this period, children have a less favorable response to the same treatment [7]. Nevertheless, most of the existing research has not explored the outcomes of delayed ophthalmic management in adults.

2. Materials and Methods

We conducted a review of 11 historical cases to examine visual outcomes that involved ophthalmic procedures after early and prolonged childhood blindness due to bilateral visual deprivation [8]. We obtained these cases from a single systematic review conducted by May et al. on the impact of delayed access to treatment for blinding conditions [8]. Early blindness was defined as within the first year of life, and prolonged blindness was defined as lasting through age 17 years or longer. From these cases, we obtained clinical information on their visual impairment, procedures that they underwent, baseline visual acuity, and postoperative visual acuity (Table 1).

3. Results

A systematic review identified cases, from 1826 to the present day, of delayed ophthalmic procedures to improve vision after early and prolonged childhood blindness [8]. The procedures involved cataract surgery, iridotomy, corneal transplantation, and prescription of aphakic spectacles. From this review, we identified 11 patients who: 1) had severely limited visual acuity before the age of 1 year, and 2) had an ophthalmic procedure performed to improve visual acuity at age 17 years or greater (Table 1). All 11 patients had some description of postoperative visual function, though it was not always in a standard form (such as Snellen or LogMAR visual acuity). Only half the patients were reported to see 20/400 or better after intervention. These patients were generally in the range of 20/250, although one patient had visual acuity of 20/100. This patient had spontaneous resorption of infantile cataracts and was corrected with aphakic spectacles at the age of 24 years [9]. Thus, the poor visual acuity was due to refractive error plus amblyopia, rather than media opacity. Based on these reports, the best visual acuity which reasonably can be expected after surgery for severe visual axis opacities throughout childhood appears to be about 20/200, and this follows a period of visual recovery and rehabilitation.

4. Discussion

Among the 11 patients we identified with limited visual acuity by age 1 year and ophthalmic procedures from age 17 years or older, eight patients had detailed reports of visual rehabilitation after their procedures, and four patients had detailed reports of visual rehabilitation for one year or greater. After removing post-operative bandages, these patients generally were able to immediately experience increased vision in the form of recognition of faces and light perception. Upon trying to observe their environment in the early days and weeks post-operatively, many of these patients reported that they felt overwhelmed. Though many could visualize objects, they reported difficulty identifying what objects they were seeing and whose faces they were looking at without using other senses, such as hearing the person’s voice.

In the detailed reports that longitudinally examined recoveries, patients seemed to acquire most of their visual benefit within 1 to 1.5 years post-operatively. Some patients underwent visual therapy in that time, such as Carlson’s patient regularly worked with a special teacher of visual rehabilitation for 1.5 years through a series of tasks to train visually guided hand movements [14]. Obtaining visual benefit may have been delayed due to the mechanisms of neuroplasticity for adult vision. Higher levels of neuroplasticity and response to amblyopia treatment are seen in early development while lower levels of neuroplasticity are observed later in life [21]. For instance, children with amblyopia who undergo management with either atropine or patching will generally experience improved visual acuity within weeks to months [22]. In contrast, a retrospective study reported that adults with monocular amblyopia whose non-amblyopic eyes suffered from disease experienced improvement in BCVA in their amblyopic eye, with peak improvement after 12 months [23]. Thus, while adults may respond to amblyopia treatment, their responses are often delayed and not as strong as those seen in children.

During this period of rehabilitation, patients reported improved vision in terms of properly perceiving colors, depth perception, and scattered objects. For instance, Gregory (1963) followed his patient, SB, who underwent cornea transplantation at 52 years of age until his death two years later. Likewise, Carlson’s patient, who underwent cataract removal with iridectomy at 23 years of age, had visual improvement within the first 1.5 years after her procedure. Carlson (1983) reported that this patient had slow visual improvement from seeing only light and colors within the first month and still did not have the ability to recognize objects without touch after nine months. After 1.5 years, she was able to incorporate her improved visual function into her day-to-day life.

Nevertheless, not every patient had a gradually progressive improvement in visual acuity post-operatively. This was the case for SK, the patient described by Ostrovsky (2009). After noting visual improvement within the first 6 months after receiving aphakic spectacles, his visual performance remained similar from 6 to 12 months after treatment. Even so, he was noted to have improvement when followed up at 18 months after treatment.

Another interesting case did not qualify for our review because the visual impairment presumably began at age 21 months of age when the patient’s mother noted whiteness in both his pupils. Fine (2002) cared for a patient, PD, who began to have denser central nuclear opacification as he grew older [24]. Though he had difficulty seeing curbs and recognizing people, his doctor managed his cataracts conservatively with atropine treatment because the lens periphery was clear. Once PD was 43 years of age, he underwent cataract removal with intraocular implantation. His baseline visual acuity of 20/80 improved to 20/40 postoperatively. In contrast to our cases of interest, PD had better baseline and postoperative visual acuity. Given that PD’s visual impairment became apparent past 1 year of age, his case may reflect the significance of early visual development despite prolonged visual impairment and delayed management.

5. Conclusions

Based on these cases, the best visual acuity which reasonably can be expected after surgery for severe visual impairment throughout childhood appears to be about 20/200, following a period of visual recovery and rehabilitation. This limited visual improvement is consistent with the irreversible visual impairment from amblyopia in individuals with early and prolonged blinding conditions. Despite delays in ophthalmic procedures, patients continue to experience benefits in their best vision. These findings underscore the importance of intervention for individuals with visual impairment, even if treatment must be delayed.