Ocular surface squamous neoplasia in Kenya

Epi and management of ocular surface - SG

Caption: Stephen Gichuhi taking a photograph of a conjunctival tumour in a study participant at Kikuyu Hospital. Nairobi KENYA.  Stephen Gichuhi


Identifying risk factors and evaluating treatments for OSSN

In East Africa, ocular surface squamous neoplasia (OSSN) is a relatively common and aggressive eye cancer affecting younger adults causing visual disability, high morbidity and even death.

Management of OSSN is challenging: the cause is unclear, people with the disease often present late, early diagnosis is problematic and tumours frequently return after surgical treatment. Studies have linked OSSN to HIV, human papilloma virus (HPV) and solar radiation. However, about 30% of cases are HIV negative and the importance of a low CD4 count has not been investigated. Some studies have found an association with HPV and others have not. The importance of vitamin A for a healthy ocular surface is known, yet its role in OSSN is not. The reasons for late presentation have not been investigated.

The diagnosis relies on clinical impression but OSSN appears similar to other conjunctival tumours and histopathology services are frequently unavailable in Africa. Treatment usually involves surgical excision; however up to 30-66% recur by three years.

We are conducting a large case-control study to investigate risk factors that may contribute to the development of OSSN and studying various molecular mechanisms that may be involved in the pathophysiology. We are evaluating a special dye called Toluidine Blue for making the diagnosis. We are investigating reasons for late presentation to try to identify factors that could hasten presentations. We are conducting a randomised controlled trial of 5-Fluorouracil chemotherapy eye-drops given after surgical excision to see if this can reduce the recurrence of the lesions.


British Council for Prevention of Blindness (BCPB) PhD fellowship for Stephen Gichuhi. The Wellcome Trust, through a Senior Research Fellowship to Matthew Burton.


The University Of Nairobi Department of Ophthalmology gave Dr Gichuhi research study leave to conduct this project. We also acknowledge the following institutions in Kenya; Kenyatta National Hospital, PCEA Kikuyu Eye Unit, Kitale District Hospital, Sabatia Eye Hospital, KAVI Institute of Clinical Research and the MP Shah Hospital.

The following institutions have provided laboratory support in the UK; UCL Institute of Ophthalmology, London School of Hygiene & Tropical Medicine and The Wellcome Trust Sanger Institute.


  • Dr Joy Kabiru (Consultant Ophthalmologist) at Kikuyu Eye Unit, Kenya.
  • Prof. Walter Jaoko (Deputy Director), KAVI Institute of Clinical Research, University of Nairobi, Kenya.
  • Dr Rhoda Munene (Consultant Ophthalmologist) and Dr Joseph Wachira (Consultant Ophthalmologist) at Kenyatta National Hospital, Kenya
  • Dr Hillary Rono (Consultant Ophthalmologist) at Kitale Eye Unit, Kenya.
  • Dr Ernest Ollando (Consultant Ophthalmologist) at Sabatia Eye Hospital, Kenya
  • Dr Mandeep Sagoo (Consultant Ocular Oncologist), Prof. Shin Ichi Ohnuma (Chair in Experimental Ophthalmology) and Prof. Phil Luthert (Director / Consultant Pathologist) at UCL Institute of Ophthalmology, London.
  • Dr Serena Nik-Zainal (Cancer Geneticist) at the Wellcome Trust Sanger Institute, Cambridge.
  • Prof. Martin Hibberd (Emerging Infectious Diseases) at LSHTM


  • Gichuhi S, Macharia E, Kabiru J, Zindamoyen AM, Rono H, Ollando E, Wachira J, Munene R, Maina J, Onyuma T, Sagoo MS, Weiss HA, Burton MJ. Topical 5-Fluorouracil following surgery for ocular surface squamous neoplasia in Kenya: a randomised, double-masked, placebo-controlled trial. Lancet Glob Health 2016; 4(6): e378-e385. Abstract.
  • Gichuhi S, Macharia E, Kabiru J, Zindamoyen AM, Rono H, Ollando E, Wanyonyi L, Wachira J, Munene R, Onyuma T, Jaoko W, Sagoo MS, Weiss HA, Burton MJ. Toluidine blue 0.05% vital staining for diagnosis of ocular surface squamous neoplasia in Kenya. JAMA Ophthalmol. 2015; 133(11): 1314-1321. Abstract.
  • Gichuhi S, Macharia E, Kabiru J, Zindamoyen AM, Rono H, Ollando E, Wanyonyi L, Wachira J, Munene R, Onyuma T, Sagoo MS, Weiss HA, Burton MJ. Clinical presentation of ocular surface squamous neoplasia in Kenya. JAMA Ophthalmol. 2015; 133(11): 1305-1313. Abstract.
  • Gichuhi S, Ohnuma A, Sagoo MS, Burton MJ. Pathophysiology of ocular surface squamous neoplasia. Exp Eye Res. 2014; 129:172-182. Abstract.
  • Gichuhi S, Onyuma T, Macharia E, Kabiru J, Zindamoyen AM, Sagoo MS, Burton MJ. Ocular rhinosporidiosis mimicking conjunctival squamous papilloma in Kenya. BMC Ophthalmology 2014 Apr 8;14(1):45. Abstract.
  • Gichuhi S, Sagoo MS, Weiss HA, Burton MJ. Epidemiology of ocular surface squamous neoplasia in Africa. Trop Med Int Health. 2013 Dec;18(12):1424-43. Abstract.
  • Gichuhi S, Irlam JH. Interventions for squamous cell carcinoma of the conjunctiva in HIV-infected individuals. Cochrane Database Syst Rev. 2013 Feb 28; 2:CD005643. doi: 10.1002/14651858.CD005643.pub3. PubMed PMID: 23450564. Abstract.

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