Continuing the keratoconus theme from the last issue, this article explores an emerging treatment approach, which can yield significant improvements to visual outcome for patients with the condition.
The first article in this series outlined the signs, symptoms and management options for keratoconus. This article concentrates on when to refer patients with keratoconus and outlines the relevance of the Athens protocol, a treatment modality that reshapes the corneal surface and strengthens the corneal stroma. This procedure can enhance unaided vision and also improve tolerance to spectacles or contact lenses. Case studies will be presented which demonstrate the effectiveness of the Athens protocol.
When to refer to a specialist corneal serviceMany patients with keratoconus can be managed with spectacles and contact lenses in optometric practice, especially in the early to moderate stages of the disease. Referral for specialist opinion should take place if:
- There is evidence of disease progression
- The practitioner does not have the necessary experience of fitting complex contact lens designs for more advanced cases
- When the best corrected visual acuity is reduced despite spectacle or contact lens correction
- Contact lens intolerance occurs due to lens discomfort
- Complications develop requiring more urgent specialist intervention, such as scarring, neovascularisation or hydrops
Corneal cross-linking (CXL) is now a recognised intervention to help prevent progression of keratoconus.1-9 The Athens protocol combines cross-linking with topographic guided laser treatment. This has the advantage of creating a more regular corneal shape and may further enhance the quality of vision.1
Following application of anaesthetic eye drops, a speculum is put in place to keep the eye open. A ring is placed over the treatment zone of the cornea and a 20% alcohol solution is applied for 30 seconds to soften the epithelium to enable manual debridement. Surface ablation using a topographic-guided excimer laser is performed to reshape the cornea. Riboflavin (vitamin B2) is then applied as a drop onto the surface of the eye every two minutes for 15 minutes.
Following this, UV light (wavelength 360–370nm and intensity 9mW/ cm2) is applied to the cornea for a further 10 minutes, with more regular applications of riboflavin drops (see Figure 1: Set up of the corneal crosslinking procedure. UV light is used to activate the riboflavin and increase the collagen bonds within the cornea. Image courtesy of Rakesh Jayaswal, Laservision). At the end of the procedure, a bandage contact lens is fitted to help reduce discomfort and to promote corneal epithelialisation. Antibiotic and anti-inflammatory eye drops are administered to prevent infection and a hyaluronic acid based lubricant issued to keep the eye comfortable during the healing period. Vision improves over the week following treatment and is usually back to normal after two to four weeks. The bandage contact lens is removed five to seven days after the initial treatment.
Simultaneous versus sequential treatment
Contradictions to the Athens protocolNot all keratoconic cases are suitable for the Athens approach and the following are important contraindications:9,12,13
- Corneal thickness <400μm at thinnest point
- Clinically significant corneal scarring
- Pregnant or breast-feeding mothers14
- Diabetics (difficult to assess the healing response)
- Previous ocular herpes10,12
- Systemic autoimmune conditions
- Ocular viral activity within the last six months
Advantages and disadvantages of Athens treatment
- Postoperative haze which reduces after three to 12 months19
- Glare especially in low light levels
- Haloes around bright lights
- Delayed epithelial healing
- Recurrent corneal erosion
- Microbial infection20,21
- Endothelial damage
- Very rarely, reactivation of herpes simplex keratitis22
The key reservation from practitioners is the long-term stability following treatment. At present, there is a paucity of data detailing vision and topography changes following treatment over more than one year.6,7,15-18 It is important to know if the treatment stops ectasia progression and stabilises keratometry readings, visual acuity and refraction over the long term. One recent study investigated the safety and efficacy of the Athens protocol over three years.9 It considered the refractive, topographic, pachymetric and visual changes in a large number of cases. Uncorrected and corrected visual acuity improved by 0.38 and 0.20 LogMAR units, respectively. Anterior keratometry readings flattened over three years and pachymetry stabilised.
Post operative follow up
Following treatment, patients should have uncorrected and corrected visual acuity monitored, along with refraction, corneal haze assessment and signs of infection checked.
Contact lens fitting can be undertaken at a minimum of one month following treatment but it is advisable to wait about three months and only when there are two stable topography readings, six weeks apart.
At present the Athens protocol is not available on the NHS; hence patients must be seen privately at an appropriate centre.Figure 2: Abnormal growth of the cornea causes the central area to become conical.
About the authors
Prashant Shah BSc, MCOptom, PGDipOphth, DipClinOptom, is an optometrist with postgraduate diplomas in ophthalmology and in clinical optometry. He works in routine practice and within a laser clinic environment. Victoria Rowe BSc, MCoptom, is an experienced optometrist who has worked for LaserVision since 2012. She also works in a paediatric clinic as well as being a community optometrist.
The authors would like to thank consultant ophthalmologists Rakesh Jayaswal and Mike Tappin for their help and support with this article.
- Kanellopoulos AJ (2009) Comparison of sequential vs same-day simultaneous collagen cross-linking and topography-guided PRK for treatment of keratoconus. J Refract Surg. 25(9):S812-S818
- Kymionis GD, Kontadakis GA, Kounis GA, et al (2009) Simultaneous topography-guided PRK followed by corneal collagen cross-linking for keratoconus. J Refract Surg.25(9):S807–S811
- Krueger RR, Kanellopoulos AJ (2010) Stability of simultaneous topography-guided photorefractive keratectomy and riboflavin/UVA cross-linking for progressive keratoconus: case reports. J Refract Surg. 26(10):S827–S832
- Kymionis GD, Portaliou DM, Kounis GA et al (2011) Simultaneous topography-guided photorefractive keratectomy followed by corneal collagen cross-linking for keratoconus. Am J Ophthalmol. 152(5):748–755
- Kanellopoulos J (2008) Limited topography-guided surface ablation (TGSA) followed by stabilization with collagen crosslinking with UV irradiation and riboflavin (UVACXL) for keratoconus (KC). Invest Ophthalmol Vis Sci. 49:E-Abstract 4338
- Kanellopoulos AJ (2012) Long term results of a prospective randomized bilateral eye comparison trial of higher fluence, shorter duration ultraviolet A radiation, and riboflavin collagen cross linking for progressive keratoconus. ClinOphthalmol. 6:97-101
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- Caporossi A, Baiocchi S, Mazzotto C et al (2006) Parasurgical therapy for keratoconus by riboflavin ultraviolet type A rays induced cross-linking of corneal collagen: Preliminary refractive results in an Italian study. Journal of Cataract and Refractive Surgery 32:837-845
- Kanellopoulos AJ, Asimellis G. (2014) Keratoconus Management: Long-Term Stability of Topography-Guided Normalization Combined With High-Fluence CXL Stabilization (The Athens Protocol). J Refract Surg. 30(2):88-92
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