Tips and tricks for maximising access to the middle cranial fossa using the superior lateral orbital portal

BACKGROUND

Transorbital endoscopic approaches are becoming increasingly popular for skull base pathologies; the superior lateral orbital portal is one such approach to the middle cranial fossa. This paper provides a technical description that maximises the surgical portal and minimises morbidity.

TECHNICAL DESCRIPTION

A superior lid crease incision is made extending laterally and the orbital rim is exposed. A subperiosteal dissection of the lateral and superior orbit is performed, with elevation of periosteum off Whitnall's tubercle, ligation of the recurrent branch of the middle meningeal artery, and identification of the superior orbital fissure. The lacrimal keyhole is then drilled away. The middle cranial fossa is accessed by drilling posterior to the orbital rim to expose: the temporalis muscle anterior-laterally, the dura of the temporal lobe posterior-laterally, the anterior cranial fossa superiorly and the periorbita medially.

CONCLUSION

These surgical steps can maximise the surgical portal and minimise morbidity, with avoidance of injury to surrounding structures.

Extrascleral extension of choroidal melanoma after iodine-125 brachytherapy treatment: a case series

BACKGROUND/OBJECTIVES

The purpose of this study is to report cases of choroidal melanoma that developed extrascleral tumour recurrence after treatment with iodine-125 brachytherapy.

SUBJECTS/METHODS

In this single-institution retrospective observational case series, all instances of biopsy-confirmed orbital melanoma after known intraocular melanoma were reviewed. Tumour characteristics, clinical course, time to recurrence, cytogenetics of initial tumour and recurrence, and presence of intraocular recurrence were documented.

RESULTS

Five cases of orbital melanoma following treatment with plaque radiotherapy are described. Tumour staging was Ia (1), IIa (2), and IIb (2). The primary lesion in four of the five appeared to have undergone complete regression for an average of 2 years, with the orbital melanoma developing after this interval. Recurrence of the intraocular tumour was seen in conjunction with an extrascleral component in two cases. Four cases ultimately underwent enucleation or exenteration; three had evidence of direct extension of tumour through the sclera. Four cases in this series had molecular characteristics associated with high metastatic risk (three patients with monosomy 3, one with BAP1 mutation).

CONCLUSIONS

High-risk tumour biology may predispose to late appearance of extrascleral melanoma despite optimal treatment and adequate control of the intraocular tumour. Extended follow-up with detailed orbital examination and imaging is recommended for this population.

Impact of COVID-19 on surgical specialist training as quantified by trainee complication rates for cataract surgery

BACKGROUND

Reduction in elective surgeries during the COVID-19 pandemic has negatively impacted surgical specialist training. Posterior capsule rupture rate (PCR), a complication of cataract surgery, is an objective measure of the quality of ophthalmic surgery. This study aimed to compare PCR pre- and post-COVID-19 in trainees and consultants.

METHODS

A single-centre consecutive cases series of cataract surgeries performed at Groote Schuur Hospital, between 1 February 2017 and 31 May 2021 were analysed. Our main outcome measure was the effect of the volume of cataract surgeries on PCRs between ophthalmology trainees and consultants before and after the COVID-19 reduction in elective surgeries on 23 March 2020.

RESULTS

During the study period, 4 157 cataract surgeries were performed (3 493 in the 38 months pre-COVID-19 and 664 in the 14 months post-COVID-19). Fourteen ophthalmology trainees and six consultants performed 2 919 and 1 238 cataract surgeries, respectively. In the trainees the PCR was 4.4% pre-COVID-19 and 10.0% post-COVID-19 (odds ratio [OR] 2.44; p < 0.001; CI 1.71-3.47; relative risk [RR] 2.29). The PCR of consultants remained unchanged with a PCR of 3.4% pre- and post-COVID-19 (OR 1.02; p = 0.97; CI 0.42-2.46; RR 1.02).

CONCLUSION

COVID-19 has caused a marked reduction in the volume of cataract surgery which has resulted in a deterioration in the performance of trainees, but not consultants, and quantifies the negative impact of the pandemic on surgical training in ophthalmology. This highlights the need to develop plans to improve surgical training during the COVID-19 recovery period.

The Global Retinoblastoma Outcome Study: a prospective, cluster-based analysis of 4064 patients from 149 countries

Background

Retinoblastoma is the most common intraocular cancer worldwide. There is some evidence to suggest that major differences exist in treatment outcomes for children with retinoblastoma from different regions, but these differences have not been assessed on a global scale. We aimed to report 3-year outcomes for children with retinoblastoma globally and to investigate factors associated with survival.

Methods

We did a prospective cluster-based analysis of treatment-naive patients with retinoblastoma who were diagnosed between Jan 1, 2017, and Dec 31, 2017, then treated and followed up for 3 years. Patients were recruited from 260 specialised treatment centres worldwide. Data were obtained from participating centres on primary and additional treatments, duration of follow-up, metastasis, eye globe salvage, and survival outcome. We analysed time to death and time to enucleation with Cox regression models.

Findings

The cohort included 4064 children from 149 countries. The median age at diagnosis was 23·2 months (IQR 11·0–36·5). Extraocular tumour spread (cT4 of the cTNMH classification) at diagnosis was reported in five (0·8%) of 636 children from high-income countries, 55 (5·4%) of 1027 children from upper-middle-income countries, 342 (19·7%) of 1738 children from lower-middle-income countries, and 196 (42·9%) of 457 children from low-income countries. Enucleation surgery was available for all children and intravenous chemotherapy was available for 4014 (98·8%) of 4064 children. The 3-year survival rate was 99·5% (95% CI 98·8–100·0) for children from high-income countries, 91·2% (89·5–93·0) for children from upper-middle-income countries, 80·3% (78·3–82·3) for children from lower-middle-income countries, and 57·3% (52·1-63·0) for children from low-income countries. On analysis, independent factors for worse survival were residence in low-income countries compared to high-income countries (hazard ratio 16·67; 95% CI 4·76–50·00), cT4 advanced tumour compared to cT1 (8·98; 4·44–18·18), and older age at diagnosis in children up to 3 years (1·38 per year; 1·23–1·56). For children aged 3–7 years, the mortality risk decreased slightly (p=0·0104 for the change in slope).

Interpretation

This study, estimated to include approximately half of all new retinoblastoma cases worldwide in 2017, shows profound inequity in survival of children depending on the national income level of their country of residence. In high-income countries, death from retinoblastoma is rare, whereas in low-income countries estimated 3-year survival is just over 50%. Although essential treatments are available in nearly all countries, early diagnosis and treatment in low-income countries are key to improving survival outcomes.

Funding

Queen Elizabeth Diamond Jubilee Trust.

Travel burden and clinical presentation of retinoblastoma: analysis of 1024 patients from 43 African countries and 518 patients from 40 European countries

BACKGROUND

The travel distance from home to a treatment centre, which may impact the stage at diagnosis, has not been investigated for retinoblastoma, the most common childhood eye cancer. We aimed to investigate the travel burden and its impact on clinical presentation in a large sample of patients with retinoblastoma from Africa and Europe.

METHODS

A cross-sectional analysis including 518 treatment-naïve patients with retinoblastoma residing in 40 European countries and 1024 treatment-naïve patients with retinoblastoma residing in 43 African countries.

RESULTS

Capture rate was 42.2% of expected patients from Africa and 108.8% from Europe. African patients were older (95% CI -12.4 to -5.4, p<0.001), had fewer cases of familial retinoblastoma (95% CI 2.0 to 5.3, p<0.001) and presented with more advanced disease (95% CI 6.0 to 9.8, p<0.001); 43.4% and 15.4% of Africans had extraocular retinoblastoma and distant metastasis at the time of diagnosis, respectively, compared to 2.9% and 1.0% of the Europeans. To reach a retinoblastoma centre, European patients travelled 421.8 km compared to Africans who travelled 185.7 km (p<0.001). On regression analysis, lower-national income level, African residence and older age (p<0.001), but not travel distance (p=0.19), were risk factors for advanced disease.

CONCLUSIONS

Fewer than half the expected number of patients with retinoblastoma presented to African referral centres in 2017, suggesting poor awareness or other barriers to access. Despite the relatively shorter distance travelled by African patients, they presented with later-stage disease. Health education about retinoblastoma is needed for carers and health workers in Africa in order to increase capture rate and promote early referral.

Global Retinoblastoma Presentation and Analysis by National Income Level

Importance

Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale.

Objectives

To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis.

Design, Setting, and Participants

A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017.

Main Outcomes and Measures

Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis.

Results

The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]).

Conclusions and Relevance

This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs.

Contralateral Precaruncular Approach to the Lateral Sphenoid Sinus-A Case Report Detailing a New, Multiportal Approach to Lesions, and Defects in the Lateral Aspect of Well-Pneumatized Sphenoid Sinuses

INTRODUCTION

Conventional surgical approaches to the lateral aspect of a well-pneumatized sphenoid sinus are associated with significant surgical morbidity. Transorbital endoscopic approaches have recently gained favor as an alternative approach to the skull base. We describe the use of a contralateral precaruncular endoscopic approach to provide a surgical pathway to the lateral aspect of the sphenoid sinus, allowing for improved and direct visualization of the surgical field, with limited morbidity.

CASE REPORT

A 60-year-old female patient, with a spontaneous cerebrospinal fluid leak from a Sternberg canal defect in the sphenoid sinus, underwent repair of the defect at Groote Schuur Hospital (Cape Town, South Africa). A contralateral precaruncular approach, using the left medial orbital portal, was utilized to access the defect in the lateral aspect of a well-pneumatized right sphenoid sinus. Computer modeling software was used to predetermine the surgical pathway, and the case was performed under navigation guidance. Adequate surgical access was obtained to the lateral sphenoid sinus and sinus defect, with superior visualization compared to a pure transnasal or transpterygoid approach to the lateral sphenoid sinus.

CONCLUSIONS

This case validates the use of computer simulation to plan and decide on the best operative approaches in skull base surgery and describes the contralateral precaruncular approach as a surgical pathway to the lateral sphenoid sinus. Advantages of the contralateral precaruncular approach include a direct trajectory toward the sinus defect, easy access with a standard 18-cm, 4-mm, 0-degree rigid endoscope, and straight instruments, with sparing of the pterygoid base and contents of the pterygopalatine fossa.

Development of the international orbital Cavernous Hemangioma Exclusively Endonasal Resection (CHEER) staging system

BACKGROUND

Orbital cavernous hemangiomas (OCH) are the most common adult orbital tumor and represent an ideal index lesion for endonasal orbital tumor surgery. In order to standardize outcomes reporting, an anatomic-based staging system was developed.

METHODS

An international, multidisciplinary panel of 23 experts in orbital tumor surgery was formed. A modified Delphi method was used to develop the cavernous hemangioma exclusively endonasal resection (CHEER) staging system with a total of 2 rounds being completed.

RESULTS

Tumors medial to a plane along the long axis of the optic nerve may be considered amenable for an exclusively endonasal resection. In select cases, tumors may extend inferolaterally if the tumor remains below a plane from the contralateral naris through the long axis of the optic nerve (ie, plane of resectability [POR]). This definition reached consensus with 91.3% of panelists in agreement. Five stages were designed based on increasing technical resection difficulty and potential for morbidity. Stages were based on the relationship of the tumor to the extraocular muscles, the inferomedial muscular trunk of the ophthalmic artery (IMT), and orbital foramina. Staging by anatomic location also reached consensus with 87.0% of panelists in agreement. Size was not included in the staging system due to the lack of agreement on the contribution of size to resection difficulty.

CONCLUSION

Endoscopic orbital tumor surgery is a nascent field with a growing, yet heterogeneous, body of literature. The CHEER staging system is designed to facilitate international, high-quality, standardized studies establishing the safety, efficacy, and outcomes of endonasal resection of OCH.

Clinical Manifestations and Cerebrospinal Fluid Status in Ocular Syphilis

PURPOSE

To review the clinical manifestations, cerebrospinal fluid findings and outcomes of patients diagnosed with ocular syphilis.

METHODS

Retrospective case review of all patients treated with ocular syphilis at Groote Schuur Hospital in Cape Town, South Africa between January 2008 and January 2013.

RESULTS

A total of 77 eyes of 49 patients were included. Panuveitis was the most common presenting sign (48.9%). A lumbar puncture was performed on 37 patients (75.5%) and 64.8% (24/37) of samples had positive treponemal testing (CSF-FTA) while 24.3% (9/37) had positive non-treponemal testing (CSF-VDRL). Elevated CSF lymphocyte cell count was a strong predictor of neurosyphilis (p = 0.06 for CSF-FTA positive samples and p = 0.03 for CSF-VDRL positive samples).

CONCLUSION

The majority of patients (64.8%) who underwent lumbar puncture had cerebrospinal fluid findings suggestive of neurosyphilis. Elevated CSF lymphocyte cell count and total protein count are highly suggestive of neurosyphilis.

Medial Buttressing in Orbital Blowout Fractures

PURPOSE

To study whether ethmoidectomy predisposes the orbit to medial wall fracture with lesser trauma.

METHODS

An interventional cadaver study of 5 heads (10 orbits); the left or right orbit was randomized to undergo endoscopic complete ethmoidectomy with the fellow orbit as control. Fractures were induced with direct globe trauma, and heads underwent CT scanning. Energy to induce fracture, peak orbital pressure at time of fracture, fracture pattern, and volume of herniated tissue were measured and analyzed.

RESULTS

Fractures were induced in both orbits of all cadavers. Experimental orbits after ethmoidectomy sustained orbital fracture at less energy required (2.14 ± 0.66 vs. 3.10 ± 0.19 J, mean difference: -0.96 ± 0.33 J, p < 0.05). Similarly, peak orbital pressure was lower for ethmoidectomized orbits than for controls (11.8 ± 8.42 vs. 28.4 ± 13.2 mm Hg, mean difference: -16.5 ± 6.9 mm Hg, p < 0.05). Orbits after ethmoidectomy were more likely to sustain medial wall involvement in fracture (100%) compared with controls (20%, p < 0.05) and pure medial wall fracture (80%) compared with controls (0%, p < 0.05). Overall volume of herniated orbital contents was not significantly different between groups (p = 0.25); volume of herniated tissue from the medial wall only was significantly greater in orbits after ethmoidectomy (mean difference: 1.01 ± -0.39 cm, p < 0.05).

CONCLUSION

Endoscopic ethmoidectomy in fresh cadavers reduces impact energy necessary to induce orbital fracture and increases the prevalence of medial wall involvement. Clinicians may wish to counsel patients undergoing endoscopic sinus surgery about these relative risks.

Use of Botulinum Toxin for the Correction of Mild Ptosis

Background: Lid margin asymmetry and its associated compensatory mechanisms might cause patients to seek treatment to improve aesthetics. Surgery might not be indicated and can potentially worsen the asymmetry in these cases. Methods: A case series of three patients was organized to illustrate the use of botulinum toxin administered to the pre-tarsal orbicularis for the correction of micro-ptosis and improved symmetry. The marginal reflex distance and tarsal platform show were measured on both sides. Measurements were made using ImageJ software on standardized frontal photographs taken pre- and post-injection. Results: The average increase in the marginal reflex distance was 0.914mm, with an average pre-tarsal botulinum toxin dose of three units. The average change in tarsal platform show between the two eyes was 0.89mm. Conclusion: Botulinum toxin application to the pre-tarsal orbicularis oculi muscle might be a suitable option for the management of small eyelid margin asymmetries.

Eyebrow Contouring with Hyaluronic Acid Gel Filler Injections

Background: The eyebrow region presents challenges for filling: the skin is thick, the three-dimensional anatomy is complex and there is a predisposition towards fat atrophy and skeletonization with aging. Hyaluronic acid gel fillers are well known for their use in the periorbital region. We report our long-term experience with eyebrow filling over a period of five years. Methods: Twenty cases of periorbital eyebrow filling with hyaluronic acid gel fillers were followed up over a period of five years. The eyebrow filling was customized based on the patient's anatomical features in a three-dimensional plane. Standardized photographs before and after the procedure in standard lighting conditions were evaluated. Results: Hyaluronic acid gel fillers were tolerated well in the eyebrow region. There were no cases with blue-gray dyschromia or prolonged edema as is the case with lower eyelid injections. The eyebrow gained volume and looked fuller immediately after the injection. There were three cases with excessive eyebrow puffiness noted on a long-term follow-up which may be the accumulated filler weighing the eyebrow. No other adverse events were noted. Conclusion: The eyebrow anatomy is a complex three-dimensional structure. Deflation in the eyebrow area along with the superior sulcus occurs with aging. Filling the eyebrow with hyaluronic acid gel fillers is a useful tool in the armamentarium of the cosmetic facial surgeon and can be used in isolation in select patients or as an adjunct to surgical rehabilitation. We believe the fillers last longer and are well tolerated in the eyebrow region due to the complex anatomy specific to this region.

Clinical Profile and Outcomes of Optic Neuritis in an HIV Prevalent Urban Community in South Africa

PURPOSE:

To determine the clinical profile, causes and response to corticosteroid therapy in patients admitted and treated for optic neuritis at a tertiary hospital in Cape Town, South Africa.

METHODS:

A retrospective case review of 117 patients with optic neuritis between January 2002 and December 2012. Demographic information, clinical presentation, course of illness, investigations performed and visual outcomes at discharge and at three month follow up were collected for analysis.

RESULTS:

60 of 117 patients (51%) had an identifiable secondary cause for optic neuritis. Of the 57 patients with idiopathic optic neuritis, 14 had features associated with demyelinating disease. HIV and syphilis accounted for 62% of secondary causes of optic neuritis. Presenting visual acuity of hand movements (HM) or worse and absence of pain with extra ocular movement were associated with poorer final visual outcomes in the idiopathic optic neuritis group.

CONCLUSION:

Optic neuritis in our patients, as elsewhere in Africa, tends to be atypical in presentation. A high proportion of patients have an identifiable secondary cause. These patients thus require more extensive investigation in order to identify causes which may influence management. Secondary optic neuritis and idiopathic atypical optic neuritis carry a poorer prognosis than typical demyelinating optic neuritis.

Using the Postoperative Visual Acuity to Monitor the Quality of Cataract Surgery: Does the Day One Visual Acuity following Cataract Surgery Correlate with the Final Visual Acuity?

PURPOSE:

Monitoring the visual acuity following cataract surgery is used as a measure of the quality of the surgery in blindness prevention programs in middle- and low-income countries. While the day 1 visual acuity is usually available, the (final) visual acuity after several weeks may not be available, as the majority of patients may not return for review. This study was undertaken to ascertain if the early and late visual acuities are correlated and if the day 1 visual acuity can be used to predict the likely final visual acuity.

METHODS:

A retrospective case note review was undertaken of all eyes having cataract surgery over a 6-month period.

RESULTS:

There was a positive correlation between the day 1 and week 6 visual acuities in both the World Health Organization categories (Spearman coefficient = 0.4666, P = 0.001) and the logMAR visual acuity scores (Spearman coefficient = 0.5425, P = 0.001).

CONCLUSION:

In blindness prevention programs in middle- and low-income countries with poor postoperative follow-up where it is not possible to document the final visual acuity in all the operated cases, there is merit in documenting and monitoring the day 1 visual acuity as a quality control measure.

How useful is visual field testing in an African glaucoma clinic?

Purpose

To investigate the usefulness of visual field testing in the diagnosis and subsequent management of glaucoma in a specialist glaucoma clinic at Groote Schuur Hospital, Cape Town, South Africa.

Methods

A retrospective case note review of 344 patients who attended the glaucoma clinic between January and June 2010.

Results

The study population consisted of 201 (58%) females and 143 (42%) males. The diagnoses included 207 (60%) cases with primary open-angle glaucoma, 58 (17%) cases with chronic angle closure glaucoma, 46 (13%) cases with secondary glaucoma, 17 (5%) cases with normal pressure glaucoma, ten (3%) cases with ocular hypertension, and six (2%) glaucoma suspects. Visual field testing contributed to the diagnosis of glaucoma in only 34 (10%) cases. A total number of 2,604 fields were performed. Of these fields, 1,931 (74%) were reliable. A baseline was reached in only 141 (53%) patients. There was evidence of field progression in only 24 (9%) cases. Changes to glaucoma treatment were based on inadequate control of intraocular pressure alone in 309 (90%) patients. Visual field progression contributed to changes in treatment in only 15 (4%) cases.

Conclusion

Visual fields are not used in the diagnosis and management of glaucoma in the majority of patients in our clinic. Patients present with advanced disease, which is easily diagnosed without the use of visual fields. Progression of fields seldom contributes to monitoring and intraocular pressure is mainly used to monitor the adequacy of treatment.

Sutured posterior chamber intraocular lenses for traumatic cataract in Africa

PURPOSE

To determine the outcomes of sutured scleral fixation of posterior chamber intraocular lenses (PC IOLs) after trauma in an African population.

SETTING

State hospital and affiliated district hospital, Cape Town, South Africa.

DESIGN

Case series.

METHODS

A retrospective review was performed of the medical records of patients in whom a sutured PC IOL had been implanted for traumatic aphakia in the preceding 5 years.

RESULTS

Eighty-five percent of the 59 patients had a significant improvement in uncorrected distance visual acuity (UDVA) at the final visit. Two-thirds of patients achieved an UDVA of 6/18 or better. Those not improving had severe preexisting macular or corneal pathology. A significant number of patients (28%) with angle recession developed ocular hypertension during the postoperative period.

CONCLUSION

After careful preoperative selection, sutured PC IOLs were effective in the visual rehabilitation of eyes with traumatic subluxated cataract in which the capsular bag could not be retained.

FINANCIAL DISCLOSURE

No author has a financial or proprietary interest in any material or method mentioned.

Ethambutol induced toxic optic neuropathy in HIV positive patients

AIM

To determine whether HIV and the use of antiretroviral therapy is a risk factor for the development of ethambutol toxic optic neuropathy. To describe the clinical course of ethambutol toxic optic neuropathy in patients with HIV and to identify prognostic factors.

METHODS

The case notes of 14 consecutive patients referred to the neuro-ophthalmology clinic were reviewed. Data regarding HIV status, antiretroviral therapy, visual function, ethambutol therapy dosage, and ethambutol therapy duration were collected and analysed.

RESULTS

Eleven of the 14 patients were HIV positive. Ten of the HIV positive patients were receiving antiretroviral therapy. The mean dose of ethambutol was 17.25mg/kg/day. No statistically significant difference in mean dose, duration of therapy, age or CD4 count was found between those who showed visual improvement and those who did not. Delay in presentation of more than one month post symptom onset was correlated with poor visual outcome (P=0.001).

CONCLUSION

HIV and, perhaps more importantly, the potential mitochondrial toxic effects of Nucleoside analogue reverse transcriptase inhibitors (NRTIs) may be a risk factor for the development of toxic optic neuropathy from ethambutol therapy via a multiple hit effect. Delay in presentation results in poor visual outcome. Regular monitoring is recommended for HIV positive patients receiving antiretrovirals and requiring ethambutol therapy in order to avoid permanent visual loss.