Cataract

Developed in collaboration with CASA Medical.

Cortical cataract - Is less common and is found in a ratio of roughly 2:3 when compared to nuclear cataract. Exposure to UVB is a risk factor. Abdominal obesity also appears to add to the risk of developing cortical cataract. There is some evidence suggesting an association between cortical cataract and dementia.

Subcapsular cataract - Is mainly seen in younger adults and is a posterior opacity. If central, the reduction in visual acuity can be severe and rapid. Systemic corticosteroid use, inhaled corticosteroid use after the fourth decade of life and alcohol use may increase the risk of developing subcapsular cataract.

Cataract may result in problems with glare. In addition, if the visual axis is affected, visual performance may be severely impaired in bright light, when the pupil is narrow. In some cases, deterioration below vision standards can occur in as little as six to twelve months. Colour vision may also be affected.

This guideline applies to the presence of cataracts, and to the surgical treatment for the condition.

The choice of IOL – multifocal, extended depth of field (EDoF), or monofocal types – is to be made between the pilot or controller and their ophthalmic surgeon, based on the likely adverse effects of the type of the lens and its potential impact on their occupation.

Multifocal IOL have characteristics that may prevent certification or may result in restrictions on the medical certificate. Monovision IOLs are a technique where one eye receives a different IOL than the other, typically one for distance vision and the other for near vision. This means that pilots or controllers will not meet CASA/ CAA NZ visual standards in both eyes. Thus, monovision IOLs are unacceptable for medical certification.

Pilot and controller information

If pilots or controllers suspect they might have or have been diagnosed with cataracts they should obtain a ME review
If pilots or controllers diagnosed with cataracts notice a change in their vision or difficulties with tolerating glare, they must contact their ME
When eye surgery (cataract removal and intra-ocular lens (IOL) implants) is being considered pilots or controllers should seek advice from their MEs or CAA NZ
A period of grounding will be required until post-surgical recovery is complete and a satisfactory review from the operating surgeon has been received. This typically 3 weeks for monofocal, and 3 months for multi-focal, including EDoF IOLs. For private and recreational pilots, all lenses are acceptable for return to flying provided the ophthalmology assessment and CAA NZ Special Eye Reports are normal.

Aeromedical implications

Effect of aviation on the condition

High levels of ultraviolet light
High reflectivity eg polished steel has high reflectivity whilst rough surfaces like concrete have low reflectivity
Flight environment contains significant sources of glare that may be unpredictable (eg clouds)

Effect of the condition on aviation

Glare - both veiling that fogs images and disabling which leads to loss of contrast of objects in one’s vision
Monocular diplopia which is double vision in one eye that disappears when the eye is covered
Degraded visual acuity
Blurring
Degraded contrast sensitivity
Degraded stereopsis or binocular vision capacity
Degraded colour vision

Effect of treatment on aviation

Post-operative recovery period after intraocular lens (IOL) implant will preclude aviation duties until vision has stabilised
Complications of surgery may lead to degraded visual function including post-operative anisometropia. As surgery is often performed one eye at a time, there is potential for significant anisometropia, which may take time to adapt to. Anisometropia leads to aniseikonia (difference in images size) if wearing spectacles. Contact lenses avoid this problem.

Approach to medical certification

Based on the condition

Corrected visual acuity that meets the required standard
Contrast sensitivity testing (eg Pillie Robinson chart thresholds)
Normal stereopsis
Colour vision that meets the required standard
Absence of glare or haloes

Based on treatment

Successful cataract surgery usually results in improvement in visual acuity and contrast sensitivity, reduction of glare, and may reduce dependence on refractive correction depending on the type of IOL. Following surgery corrective lenses may be necessary to meet the vision standards.

Complications of cataract surgery can include:

residual refractive error or unexpected refractive outcome
monocular vision or binocular rivalry
reduced visual acuity
IOL location instability
capsular opacification
anterior or posterior segment infection, oedema
choroidal haemorrhage, retinal detachment, or cystoid macular oedema

Demonstrated stability

Stable visual acuity meeting standards (with or without acceptable correction)
No problems with glare, night vision, halos, diplopia, or bright light
Absence of symptoms after a reasonable period of neuroadaptation. This may vary depending upon the type of IOL implanted
Any anisometropia is less than 2.0 dioptres following recent surgery, or 2.5 dioptres if present for 6 months or longer, and is well tolerated
Recommended grounding period after uncomplicated surgery are:
- Monofocal IOL – at least three weeks
- EDOFs IOL – at least three months
- Multifocal IOL – at least three months

Risk assessment protocol - information required

New cases

Ophthalmologist’s report
- Confirmed diagnosis
- Aetiology (History of eye trauma, steroids etc)
- Details of surgery, including IOL parameters
- Any haloes, glare or diplopia
- Follow-up plan
CAA NZ Eye Report
- Including test for contrast sensitivity function for each eye
- Colour vision assessment with colour filtering IOLs
- Test for glare
Clearance
- By ME, based on CAA NZ Eye Report
- If all Grey table criteria not met review by CAA AvMed is needed
- Monovision IOLs require referral to CAA NZ AvMed

Renewal

CAA NZ Eye report after 12 months

ME aeromedical decision guide

If ALL criteria in the table below the ME may issue a medical certificate to the pilot or controller. Evidence supporting the ME’s decision (for example reports and results) must be sent to CAA NZ.

ME must confirm	Tick
Cataracts without surgical treatment Asymptomatic – no visual symptoms, problems with glare, or night vision Vision standards met Eye report – satisfactory visual acuity, glare tolerance and contrast sensitivity
Initial issue following cataract extraction and IOL insertion
No problems with glare, night vision, halos, diplopia, bright light, light streaks, starbursts, light arcs, flashes of lights, shadows or lines
Minimum grounding period met- Monofocal IOL – at least three weeks EDOFs IOL – at least three months Multifocal IOL – at least three months Monovision IOLs not implanted
All eye surgeon reports reviewed and no adverse surgical outcomes
CAA NZ eye report – visual acuity standards met (with acceptable correction if needed) Glare and contrast sensitivity testing satisfactory Colour vision testing if colour filters used with IOL eg blue filter Anisometropia – no symptoms and does not exceed 2.5 dioptres
Renewal issue 12 months after cataract surgery CAA NZ eye report satisfactory (as above)
ME considers safe to certify

An AMC referral to CAA NZ Aviation Medicine teams 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.

Recommended conditions for medical certificate:

CAA Special Eye report required 12 months after cataract surgery
CAA Special Eye report required every 12 months to assess stability of cataract (if no surgical procedure has been undertaken)

ME letters

Cataract medical certificate letter [DOCX 21 KB]

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