Developed in collaboration with CASA Medical.
Keratoconus is a bilateral and asymmetric disease which results in progressive thinning and steeping of the cornea leading to irregular astigmatism and decreased visual acuity. The cause is mostly unknown but can run in families. The main symptoms include image distortion, sensitivity to light, monocular double vision and seeing halos around bright lights. Treatment, if required, includes intracorneal ring segments / keraring, corneal crosslinking, contact lenses or in more severe cases corneal transplant. There are stand down periods associated with treatment.
Certification is possible when the condition and any treatment response to vision correction and treatment is stable. A shortened certification period may be required to allow for regular monitoring of vision. However, if the condition remains mild and has proven itself to be stable over several years, a reduced surveillance may later be considered.
Due to the progressive nature of this condition, and its effects on vision regular optometrist / ophthalmologist review will be required. If the visual requirements can only be met with contact lens restrictions may be applied on the medical certificate.
This condition may progress and may affect future certification decisions.
This guidance should be used for applicants diagnosed with keratoconus by an Ophthalmologist or Optometrist.
Pilot and controller information
- When Keratoconus is first diagnosed you must report this to your ME or CAA
- If new treatment is recommended eg contact lenses, cross linking procedures, corneal transplant you must inform their ME or CAA
- You must stop flying or operating if there are changes in your vision or you are about to start any treatment or surgery
Aeromedical implications
Effect of aviation on the condition
- Glare from airport lights and beacons
- Haloes
- Low contrast environment at night or in bad weather may further impact visual performance.
- Dry and cold air of aircraft environment may cause contact lens intolerance.
Effect of the condition on aviation
- Blurring, glare and distorted vision reduce ability to acquire targets at a distance
- Impaired ability to read instruments, to see and avoid airborne hazards
- Impaired ability to read documents and maps
- Poor vision may affect spatial orientation and situation awareness
- Progression leads to deteriorating visual function over time
Effect of treatment on aviation
- Contact lens use may result in corneal irritation and infection
- Degree of recovery of vision after surgery or surgical complications may impact certification
Approach to medical certification
Based on the condition
- Severity of keratoconus
- Risk of acute visual impairment from corneal hydrops or any other complication
- Variability of visual function e.g. instability of acuity
- Degree of anisometropia – this should be < 2.5 dioptres
- Hard contact lens, often used in keratoconus, are more prone to dislodgement
- Risk of disease progression
Based on treatment
- Conservative vs surgical treatment options, depending on severity
- Tolerance to treatment with rigid gas permeable contact lenses
- Effectiveness of treatment stabilising vision
Demonstrated stability
- Stable visual function that meets the visual standard during the period of certification
- Stable response to treatment, during the period of certification
- Specific grounding period is determined by the intervention preformed, any complications encountered and recovery.
- Potential minimum period of grounding after intervention are:
- New contact lens – 2 weeks
- Intracorneal ring segments / keraring – 2 weeks
- Corneal cross-linking – 3 months
- Corneal transplant – 6 months
Risk assessment protocol - information required
New cases
A report from an Ophthalmologist with respect to:
- Diagnosis
- History
- presenting symptoms
- nature of condition
- severity of condition or complications e.g. advanced keratoconus, corneal hydrops
- Other relevant medical history (specifically comment on the presence of any of the following)
- distracting distortions, glare/flare, monocular diplopia or ghost images
- unstable refraction
- uncorrectable refractive error
- contact lens tolerance, allergic reactions (e.g. giant papillary conjunctivitis), corneal abrasions, neovascularization
- corneal scarring
- Impairment or loss of function
Clinical findings:
- CAA NZ Special Eye Report, including:
- vision (near, intermediate and distance) - uncorrected and corrected including stand-by correction and the type of correction
- refractive correction
- tolerance of refractive correction
- retinal examination
- slit lamp examination
- corneal topographies (colour copy)
- contrast sensitivity assessment for each eye individually
- Treatment
- recent past and ongoing treatment must be detailed
- specify treatment (spectacles, contact lens, cross linking, corneal transplant)
- comment whether correction to visual standards can be achieved with spectacles
- ocular and other current and recent past medications (name, dose, start and finish dates, frequency)
- surgical reports
- Prognosis and follow up plan.
Renewal
CAA NZ Special Eye report with respect to:
- Clinical progress
- Clinical findings (as applicable) and assessment including
- vision (near, intermediate and distance) - uncorrected and corrected including stand-by correction and the type of correction
- refractive correction
- tolerance of refractive correction
- retinal examination
- slit lamp examination
- corneal topographies (colour copy)
- contrast sensitivity assessment
- Treatment:
- details of any interventions / surgery
- Prognosis and follow up plan.
ME decision guide
If ALL the criteria in the table below for an applicant with keratoconus are met, the applicant meets the acceptable criteria for certification by the ME. Evidence supporting the ME’s decision (for example reports and results) must be sent to CAA.
An AMC referral CAA NZ AvMed is required if a pilot’s or controller’s condition does not meet all the above criteria and they consent to their condition being considered under flexibility to the CAR 67 rules.
ME letters
Keratoconus medical certificate letter [DOCX 21 KB]
