Outcomes of the Boston Type I Keratoprosthesis as the Primary Penetrating Corneal Procedure

Boston Keratoprosthesis type 1 (KPro) without contact lens wearing in end-stage corneal disease: The APEC experience

PURPOSE

To report the visual outcomes and survival analysis of keratoprosthesis without contact lens wearing in a tertiary eye care hospital in Mexico City, Asociación Para Evitar La Ceguera (APEC, Coyoacán, México).

DESIGN

Retrospective cohort with survival analysis.

PARTICIPANTS

Twenty-three eyes (22 patients) received KPro type 1 between 2015 and 2020 with a follow-up time of three years.

METHODS

We included analyzed data about past medical history, preoperative diagnosis, best-spectacle visual acuity (BSCVA), postoperative complications and retention rate. Univariate, bivariate and survival analysis were performed and reported.

RESULTS

The mean age was 58 ± 13.5 years (SD). 60.86% were male patients (14 eyes). Twelve-eyes (52%) achieved a BSCVA of 20/200 or better in the first and second year of follow-up. At 3 years, only 35% achieved 20/200 or better (BSCVA). Retention rate of Boston type 1 KPro was 87% (20 eyes) at 3 years follow-up. The most common complication was retroprosthetic membrane (RPM) which occurred in 9 eyes (39.1%), followed by corneal melting in 7 eyes (30.4%).

CONCLUSIONS

We report the results of a retrospective cohort of twenty-three eyes (22 patients) who were implanted with a Boston type 1 KPro without contact lens wearing to treat corneal blindness. BSCVA improved significantly in most patients achieving 20/200 or better at the 2-year follow-up. Retention rate was 87%, with the presence of RPM as the most common complication.

Anatomical and functional outcomes of Boston type I keratoprosthesis as primary penetrating corneal procedure in high-risk and non-high-risk cases

PURPOSE

To analyze the anatomical and functional results of Boston type I keratoprosthesis (B1-KPro) as a primary corneal procedure in high-risk (HR) cases and non-high-risk (NHR) cases.

METHODS

In this retrospective interventional case series, all patients who underwent B1-KPro at a single center between January 2006 and March 2021 were reviewed and identified. Cases were classified according to the primary diagnosis. Anatomical failure was considered in the case of prosthesis extrusion or phthisis bulbi. Functional failure was a postoperative corrected distance visual acuity (CDVA) ≥ 1.3 LogMAR (≤ 0.05 decimal) at the end of the follow-up period.

RESULTS

Twenty-three eyes were included for analysis. Thirteen eyes were classified as HR and 10 as NHR. The mean age was 46.5 ± 26.5 years (5-84 years) in the HR group and 49.5 ± 26.9 years (2-78 years) in the NHR group. The mean follow-up was 42.0 ± 35.9 months (1.5-118 months) in HR and 44.8 ± 38.8 months (1-107 months) in NHR. Three eyes in the HR and none in the NHR group showed anatomical failure. Functional failure was reported in 5/13 eyes in the HR and 8/10 in the NHR group. Functional cumulative survival probability was 92% and 82% for the HR group at 1 and 2 years, respectively. In the NHR group, it was 27% at both times. No significant differences were found between groups, except for functional survival in the HR group due to better visual potential of the eyes.

CONCLUSIONS

B1-KPro as a primary corneal procedure is a valid option for visual rehabilitation in high-risk cases.

The Boston Keratoprosthesis-The First 50 Years: Some Reminiscences

Millions of people worldwide are bilaterally blind due to corneal diseases including infectious etiologies, trauma, and chemical injuries. While corneal transplantation can successfully restore sight in many, corneal graft survival decreases in eyes with chronic inflammation and corneal vascularization. Additionally, the availability of donor cornea material can be limited, especially in underdeveloped countries where corneal blindness may also be highly prevalent. Development of methods to create and implant an artificial cornea (keratoprosthesis)may be the only option for patients whose eye disease is not suitable for corneal transplantation or who live in regions where corneal transplantation is not possible. The Boston keratoprosthesis (B-KPro) is the most commonly implanted keratoprosthesis worldwide, having restored vision in thousands of patients. This article describes the initial design of the B-KPro and the modifications that have been made over many years. Additionally, some of the complications of surgical implantation and long-term care challenges, particularly complicating inflammation and glaucoma, are discussed. Expected final online publication date for the Annual Review of Vision Science, Volume 8 is September 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Retroprosthetic Membrane Formation in Boston Keratoprosthesis Type 1: Incidence, Predisposing Factors, Complications, and Treatment

PURPOSE

The purpose of this study was to evaluate the incidence, rate of formation, and risk factors of retroprosthetic membrane (RPM) after Boston type 1 keratoprosthesis (BKPro) as well as identify secondary complications linked to its formation and describe its treatment.

METHODS

This was a retrospective cohort study. One hundred thirty-three eyes of 115 patients who underwent BKPro implantation at the Centre Hospitalier de l'Université de Montréal from 2008 to 2017 were included with at least 1-year follow-up. Charts were reviewed, and data were collected, including incidence of RPM formation, preoperative and intraoperative risk factors, postoperative complications, and treatment modalities.

RESULTS

The mean follow-up was 5.5 years, and 39% (n = 52) of eyes developed RPM. No etiologies were found to be significantly associated with RPM development. Simultaneous lensectomy and simultaneous intraocular lens extraction were respectively positively and negatively correlated with RPM development [odds ratio (OR): 0.3590, 95% CI: 0.1629-0.7570, P = 0.0097; OR = 2.646, 95% CI: 1.273-5.585, P = 0.0086, respectively]. As for postoperative complications, the strongest correlation was between RPM and retinal detachment (OR = 6.16, 95% CI: 2.14-16.14; P = 0.0004). RPM development was also positively associated with the development of hypotony and corneal melt. Nd:YAG membranectomy was the most common treatment, performed in 83% of eyes with RPM (n = 24), with 58% resolution.

CONCLUSIONS

More than one third of patients who undergo BKPro will develop RPM, requiring close monitoring for retinal detachment. Simultaneous intraocular lens extraction seems protective, whereas simultaneous lens extraction increases the rate of RPM formation significantly. Nd:YAG membranectomy can be used as an initial noninvasive approach.

The treatment of end-stage corneal disease: penetrating keratoplasty compared with Boston type 1 keratoprosthesis

Penetrating keratoplasty (PKP) yields excellent results for restoring vision in end-stage corneal diseases. However, its success is limited to high-risk diseases such as aniridia, chemical burns, autoimmune corneal diseases, and herpetic eye disease. Boston type 1 keratoprosthesis (BKPro) offers another option to these patients. Since 1992, improvements in perioperative management and device construction have significantly increased the use of BKPro worldwide and challenged the therapeutic role of PKP in these patients. This review aims to evaluate BKPro's place in the treatment algorithm of these high-risk patients to assist surgeons' decision-making. PKP and BKPro are compared in three outcome categories: visual acuity, graft retention and failure, and complications profile. Special attention is given to comparing secondary BKPro versus repeated PKP as well as primary BKPro versus primary PKP. We conclude that secondary BKPro bears a better prognosis than repeated PKP in most high-risk patients. Similarly, primary BKPro likely confers improved outcomes over primary PKP in most high-risk recipients. However, current evidence is based on retrospective designs, and controlled prospective randomized trials are required to validate these conclusions.

Artificial Cornea: Past, Current, and Future Directions

Corneal diseases are a leading cause of blindness with an estimated 10 million patients diagnosed with bilateral corneal blindness worldwide. Corneal transplantation is highly successful in low-risk patients with corneal blindness but often fails those with high-risk indications such as recurrent or chronic inflammatory disorders, history of glaucoma and herpetic infections, and those with neovascularisation of the host bed. Moreover, the need for donor corneas greatly exceeds the supply, especially in disadvantaged countries. Therefore, artificial and bio-mimetic corneas have been investigated for patients with indications that result in keratoplasty failure. Two long-lasting keratoprostheses with different indications, the Boston type-1 keratoprostheses and osteo-odonto-keratoprostheses have been adapted to minimise complications that have arisen over time. However, both utilise either autologous tissue or an allograft cornea to increase biointegration. To step away from the need for donor material, synthetic keratoprostheses with soft skirts have been introduced to increase biointegration between the device and native tissue. The AlphaCor™, a synthetic polymer (PHEMA) hydrogel, addressed certain complications of the previous versions of keratoprostheses but resulted in stromal melting and optic deposition. Efforts are being made towards creating synthetic keratoprostheses that emulate native corneas by the inclusion of biomolecules that support enhanced biointegration of the implant while reducing stromal melting and optic deposition. The field continues to shift towards more advanced bioengineering approaches to form replacement corneas. Certain biomolecules such as collagen are being investigated to create corneal substitutes, which can be used as the basis for bio-inks in 3D corneal bioprinting. Alternatively, decellularised corneas from mammalian sources have shown potential in replicating both the corneal composition and fibril architecture. This review will discuss the limitations of keratoplasty, milestones in the history of artificial corneal development, advancements in current artificial corneas, and future possibilities in this field.

Infectious Keratitis After Boston Type 1 Keratoprosthesis Implantation

PURPOSE

To identify the incidence, risk factors, and outcomes of infectious keratitis after Boston type 1 keratoprosthesis (kpro) implantation.

METHODS

Retrospective case series of kpro procedures at the Stein Eye Institute and the Centre Hospitalier de l'Université de Montréal between May 1, 2004, and December 31, 2018. Data were collected regarding ocular history, operative details, postoperative management, microbiologic profile, treatment, and outcomes. Log-rank test and Cox proportional hazard ratio (HR) were used to evaluate for an association between risk factors and outcomes.

RESULTS

A total of 349 kpro procedures were performed in 295 eyes of 268 patients. Fifty-seven cases of presumed infectious keratitis were identified after 53 procedures (15.2%) in 50 eyes (16.9%) of 49 patients (18.3%). The incidences of culture-positive bacterial and fungal keratitis were 0.014 and 0.004 per eye-year, respectively. Persistent corneal epithelial defect formation (P < 0.001) and cicatricial disease (HR: 1.98, 95% confidence interval, 1.02-3.83) were associated with a significantly higher incidence of infectious keratitis. For the 53 cases with a known outcome, medical therapy achieved resolution of infection in 34 cases (64.2%), whereas kpro explantation was required in 19 cases (35.8%). Infectious keratitis was associated with an increased risk for kpro explantation (HR: 3.09, 95% confidence interval, 1.92-4.79).

CONCLUSIONS

Infectious keratitis develops in approximately 17% of eyes after kpro implantation, with a higher rate of culture-positive bacterial than fungal keratitis. The observed rate of microbial keratitis suggests the need for additional topical antimicrobial prophylaxis in eyes at higher risk, such as those with preexisting cicatricial disease or postoperative persistent corneal epithelial defect formation.

Challenges in management of the Boston Keratoprosthesis Type 1

PURPOSE OF REVIEW

The Boston Keratoprosthesis Type 1 was pioneered by Claes Dohlman several decades ago. Since its inception, the device has undergone multiple revisions to address challenges associated with retroprosthetic membrane formation, retention, extrusion, stromal melt and endophthalmitis. Although visual outcomes and retention rates have improved, challenges, especially glaucoma, remain.

RECENT FINDINGS

The Boston Keratoprosthesis Type I device has seen an increase in popularity because of the improvement in rates of retention and visual rehabilitation. Recent outcome studies have allowed clinicians to identify diagnoses and indications that can lead to more favorable results with the Boston Keratoprosthesis Type I device.

SUMMARY

The Boston Keratoprosthesis Type I device continues to play a vital role in visual rehabilitation for eyes with very low chance of realistic allograft survival -- such as in eyes where corneal grafting is considered high-risk: eyes with corneal limbal stem cell failure, extensive deep corneal stromal neovascularization, and multiple allograft failures. This review article summarizes the perioperative and postoperative challenges, as well as other considerations associated with the device.

Short-Term Outcomes of Pediatric Keratoprosthesis With the Near-Complete Conjunctival Flap

PURPOSE

The Boston keratoprosthesis (KPro) has been used for certain indications in pediatric patients with congenital corneal opacities. Here, we describe the use of a near-complete conjunctival flap at the time of Boston type 1 KPro surgery in pediatric patients, with the goal of improving pediatric KPro outcomes.

METHODS

We performed a retrospective chart review of 21 eyes from 16 patients who received their first KPro before the age of 18 years at a tertiary care center in Rochester, NY. Surgeries were performed between 2011 and 2017 (3 years before and after the incorporation of a conjunctival flap, which began in 2014 as part of the pediatric KPro procedure). Patients who had a minimum 1-year postoperative follow-up, or had corneal melts within 1 year of KPro implantation, were included in our study. The main outcome measure in this study was a comparison of the number of complications that required surgical intervention, including retroprosthetic membrane, corneal melt, retinal detachment, and endophthalmitis, in eyes that received KPro implantation without a conjunctival flap compared with eyes that received KPro implantation with a conjunctival flap. Change in the visual acuity up to 1 year postoperatively was also measured.

RESULTS

Ten eyes received KPro with no conjunctival flap, and 11 eyes received KPro with a near-complete conjunctival flap. After 1-year postoperative follow-up, eyes receiving a KPro with a conjunctival flap had fewer KPro-related complications requiring surgical intervention (5 vs. 16, P = 0.0002). Corneal melt was seen in 2 of 11 (18%) eyes in the conjunctival flap group and 5 of 10 (50%) eyes in the nonflap group (P = 0.12). No eyes developed endophthalmitis in the flap group, whereas 1 of 10 (10%) eyes developed endophthalmitis in the nonflap group. Visual acuity at 1-year follow-up improved in 9 of 11 (82%) eyes in the flap group compared with 5 of 10 (50%) eyes in the nonflap group (P = 0.3).

CONCLUSIONS

Implementation of a conjunctival flap in pediatric KPro may help decrease the short-term postoperative complications requiring surgical procedures and may lead to improved visual acuity after 1 year. Further investigation, including longer-term follow-up, is needed to better understand how the described technique affects surgical outcomes in children.

Surgical Management and Recent Advances in Chemical Injury: A 5-year Review

Purpose: To review the surgical management options in ocular chemical burn, including newer advances.Methods: Online literature search of published articles over last 5 years on surgical management of ocular chemical burn and newer advances were performed on December 30, 2020.Results: Following literature search and screening using adequate filters, 67 review articles on surgical management of ocular chemical burns were retrieved. The review talks about the surgical management options starting from Debridement in acute stage to various visual rehabilitative procedures in the chronic stage. The review also highlights the evolving surgical advances in this field.Conclusion: It is imperative to choose adequate surgical tool wherever applicable; current review discusses the role of each surgical option at different clinical stages in detail.

[Treatment of vascularized high-risk eyes with a Boston keratoprosthesis]

BACKGROUND

In severely compromised and vascularized high-risk eyes, the Boston keratoprosthesis procedure is often the last treatment option. The transparency of the optics is not impaired by endothelial immune reactions.

METHODS

This review article discusses relevant literature as well as our own data and experiences with the Boston keratoprosthesis in high-risk eyes. The relevant complications as well as the postoperative management are discussed.

RESULTS

In more than 60% of the high-risk eyes a long-term increase in visual acuity can be achieved. Keratoprosthesis retention rates show a variable span with reported mean 5‑year retention rates of 75%. The most common postoperative complications include the formation of a retroprosthetic membrane and keratolysis in up to 50% each. More than 70% of the eyes already suffer from (secondary) glaucoma preoperatively, so that glaucoma surgery is performed simultaneously in at least 20% of cases and in the postoperative course further antiglaucomatous surgery is necessary in up to 31%. Vitreoretinal complications include, in particular, sterile vitritis and infectious endophthalmitis but persistent hypotonia is also described in one third of patients.

CONCLUSION

The Boston keratoprosthesis is an alternative to conventional corneal replacement if the prognosis for allogeneic transplants is poor. Postoperative complications are common; therefore, postoperative management plays an important role. For vascularized high-risk eyes, however, it is often the only remaining option for visual rehabilitation.

Time to achieve best postoperative visual acuity following Boston keratoprosthesis surgery

BACKGROUND/AIMS

To evaluate the time needed for patients with Boston type 1 keratoprosthesis (KPro) to reach their best-corrected visual acuity (BCVA) and all contributing factors.

METHODS

We retrospectively reviewed 137 consecutive eyes from 118 patients, measured how long they needed to reach their BCVA and looked at factors that might affect this time duration including patient demographics, ocular comorbidities and postoperative complications.

RESULTS

The mean follow-up was 5.49 years. The median time to BCVA postoperatively was 6 months, with 47% of patients achieving their BCVA by 3 months. The mean best achieved logMAR visual acuity was 0.71, representing a gain of 6 lines on the Snellen visual acuity chart. Postoperative glaucoma, retroprosthetic membrane (RPM) and endophthalmitis prolonged this duration. We found no correlation between the following factors and time to BCVA: gender, age, indication for KPro surgery, primary versus secondary KPro, number of previous penetrating keratoplasties, previous retinal surgery, intraoperative anterior vitrectomy and preoperative glaucoma.

CONCLUSION

In our retrospective cohort, the majority of subjects reached their BCVA between 3 and 6 months after KPro implantation. This duration was significantly prolonged by the development of postoperative glaucoma, RPM and endophthalmitis.

Long-term outcomes following primary versus secondary Boston keratoprosthesis type 1 implantation

BACKGROUND/AIMS

To compare long-term outcomes of primary versus secondary (postgraft failure) Boston keratoprosthesis type 1 (KPro) implantation.

METHODS

Medical records of patients at the Centre hospitalier de l'Université de Montréal having undergone KPro implantation between 2008 and 2017 were reviewed and included if they had a preoperative Snellen best-corrected visual acuity (BCVA) of 20/100 or worse and a minimum of 5 years of follow-up. Eighty-two eyes were separated into two cohorts (40 primary, 42 secondary KPro) and BCVA, complications and device retention were evaluated between groups.

RESULTS

BCVA improved from baseline in both groups at each year; this was significant at all five postoperative years in the primary group and the first 3 years in the secondary group (p<0.05). Mean BCVA was similar between groups at 5 years (logarithm of minimal angle resolution 1.3±0.8 in the primary group vs 1.5±0.8 p<0.05). Idiopathic vitritis, choroidal detachment and new glaucoma occurred more after primary KPro (n=7, 17.5% vs n=1, 2.4%; n=11, 27.5% vs n=3, 7.14% and n=14, 35% vs n=6, 14%, respectively; p<0.05). Primary KPro had lower retention (n=28, 70% vs n=38, 91%, p<0.05) at final follow-up. There was more aniridia in the primary group (n=19, 48% vs n=6, 14%, p<0.01). Within each group, 50% of removals occurred in aniridic eyes.

CONCLUSION

Primary KPro yielded favourable long-term visual outcomes but had more complications and lower retention rates than secondary KPro, likely explained by preoperative indications. Primary device implantation represents a favourable option for patients for whom grafts are likely to fail.

Outcomes of the Boston type 1 and the Aurolab keratoprosthesis in eyes with limbal stem cell deficiency

PURPOSE

To analyse the outcomes of keratoprosthesis in eyes with limbal stem cell deficiency (LSCD) and to compare the outcomes in two different keratoprosthesis devices.

METHODS

This was a single-centre retrospective comparative case series which included 81 eyes of patients with severe bilateral corneal blindness secondary to LSCD. The patients underwent either Boston type 1 keratoprosthesis (Boston Kpro, n=44) or Aurolab keratoprosthesis (AuroKpro, n=37) implantation. The primary outcome measures of anatomical retention and functional recovery of 20/200 or better visual acuity at yearly time points until 5 years of follow-up were compared between the two groups.

RESULTS

The most common indication overall was chemical injury (64.2%). Anatomical retention rates were similar in the Boston Kpro (30/44, 68.2%) and AuroKpro (23/37, 62.2%) groups (p=0.89). Kaplan-Meier survival rates at 5 years of follow-up were greater for the Boston Kpro group with respect to both anatomical retention (58.51%±9% vs 43.8±12%; p=0.23) as well as functional recovery (42.61%±8% vs 35.03±10%; p=0.9); these differences were not statistically significant. Overall, the most common complication was new-onset glaucoma (59%; 48/81). The difference in incidence rate of this complication was not statistically significant among the two groups (p=0.09).

CONCLUSION

Keratoprosthesis is an effective treatment option for patients with corneal blindness secondary to LSCD. In a setting where LSCD is a common cause of corneal blindness, the AuroKpro, when available can be considered an alternative to the Boston Kpro to achieve anatomical and functional success in patients who otherwise would not have access to this device.

Boston Type 1 Keratoprosthesis: Updated Perspectives

The use of Boston type 1 keratoprosthesis (BKPro) has significantly increased worldwide. It is no longer considered a procedure of last resort but a reasonable option for patients with otherwise poor prognosis for a traditional penetrating keratoplasty. BKPro was approved by the Food and Drug Administration in 1992 for bilateral severe corneal blindness due to multiple corneal transplant failure. Over the years, indications have extended beyond recurrent immunologic rejection to include other conditions such as chemical injury and other causes of bilateral limbal stem cell deficiency, extensive corneal neovascularization, neurotrophic corneas and hypotony, among others. Numerous advances in the design of the BKPro, improvement of preoperative, intraoperative and postoperative management have resulted in favorable outcomes and a reduction in postoperative complications. Accordingly, many studies have shown that implantation of this device is highly effective in restoring vision with very good short-term outcomes. However, due to the lifetime risk of sight-threatening complications after BKPro implantation, a longer follow-up period should provide outcomes that are more realistic. In this review, the authors examined only the results of publications with an average of at least 2 years of follow-up. The overall intermediate to long-term visual outcomes and retention rate in BKPro seem to be favorable. However, autoimmune diseases and cicatrizing conditions continue to show a higher incidence of postoperative complications that require further management.

Bilateral Boston keratoprosthesis type 1 in a case of severe Mooren's ulcer

INTRODUCTION

Mooren's ulcer is a painful, inflammatory chronic keratitis that affects corneal periphery, progressing centripetally, ultimately ending in perforation. The first line of treatment includes systemic immunomodulators, with surgery being the last option. We present a case of bilateral Boston keratoprosthesis implantation for severe Mooren's ulcer that responded differently in each eye.

CLINICAL CASE

A 32-year-old male with corneal opacification, anterior staphylomas, vision of hand movement, was started on systemic immunosuppression with cyclosporine. After two failed penetrating keratoplasties in each eye, high intraocular pressure despite diode cyclophotocoagulation, and cystic macular edema, we performed Boston keratoprosthesis type 1 in both eyes. The right eye responded initially well, with a best-corrected visual acuity of 20/80 and normal intraocular pressure. The left eye presented high intraocular pressure, which required cyclophotocoagulation, ultimately resulting in hypotony. Boston keratoprosthesis was performed but had peripheral corneal necrosis that progressed despite amniotic membrane transplantation and aggressive intensive treatment with medroxyprogesterone, autologous platelet-rich-in-growth-factors eye drops, and oral doxycycline. Thus, replacement of the semi-exposed Boston keratoprosthesis with tectonic penetrating keratoplasty was necessary. However, both eyes developed phthisis bulbi with final visual acuity of perception of light with poor localization.

CONCLUSION

Mainstay treatment of Mooren's ulcer is systemic immunomodulation. Surgical treatment must be considered only when risk of perforation, preferably with inflammation under control. Penetrating keratoplasty frequently fails, and Boston keratoprosthesis may be a viable option. However, postoperative complications, especially uncontrolled high intraocular pressure, corneal necrosis, and recurrence of Mooren's ulcer may jeopardize the outcomes and need to be addressed promptly with intensive topical and systemic treatment.

Management of Congenital Aniridia-Associated Keratopathy: Long-Term Outcomes from a Tertiary Referral Center

PURPOSE

To report the outcomes of medical and surgical management for congenital aniridia-associated keratopathy (AAK) over a long-term follow-up period.

DESIGN

Retrospective, comparative case series.

METHODS

Medical records of patients diagnosed with congenital aniridia were retrospectively reviewed. Age, sex, ethnicity, follow-up time, AAK stage, noncorneal abnormalities, ocular surgeries, and complications were recorded. The visual acuity equivalent (VAE), approximate Early Treatment Diabetic Retinopathy Study (appETDRS) letter score, was calculated using recorded Snellen visual acuities.

RESULTS

A total of 92 eyes of 47 patients (31 females) with mean age of 48.0 ± 18.0 years and mean follow-up of 78.6 ± 42.2 months were included. At the initial visit, 12 eyes (13%) were classified as Stage I AAK, 33 eyes (35.9%) were Stage II, 25 eyes (27.2%) were Stage III, 17 eyes (18.5%) were Stage IV, and 5 eyes (5.4%) were Stage V. Limbal stem cell transplantation (LSCT) and Boston keratoprosthesis (KPro) were frequently performed in eyes with Stages III-V. These advanced corneal surgeries significantly improved the median (95% confidence interval [CI]) of calculated appETDRS scores from 2 (0-20) to 26 (15-41) (Snellen values, 20/20,000 to 20/300; P = 0.0004). Patients with earlier Stages (I-II) of AAK were managed medically and had stable visual acuity through their final visits (appETDRS score of 26 [20-35] to 35 [26-35]; Snellen, 20/300 to 20/200; P > 0.05). The appETDRS VAE was significantly improved from 20 (0-35) to 30 (20-55), Snellen, 20/400 to 20/250, following LSCT (P = 0.021) and from 2 (0-20) to 2 (0-41) after KPro; Snellen, 20/20,000 VAE but with improved 95% CI after follow-up (P = 0.019).

CONCLUSIONS

With proper characterization and staging of AAK, individualized medical and advanced surgical interventions preserves and improves visual acuity.