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normal, clear lens has been used as a treatment for high myopia. In most situations, the lens is removed
because it is cataractous and optical correction will be required in the form of spectacles, contact lenses,
intraocular lenses or a combination of these.
Spectacle correction of aphakia
11.4.38 In most patients the strength of aphakia spectacles is such that the induced magnification,
distortion and loss of peripheral visual field precludes their use in the aviation environment. There may be some
exceptions in persons previously highly myopic whose aphakia spectacles are of low or moderate power but,
generally speaking, aphakia spectacles are not acceptable for flight crew or air traffic controllers.
Contact lens correction of aphakia
11.4.39 Almost all the optical problems associated with aphakia spectacles can be avoided by the use of
contact lenses. Many aphakic patients obtain good or excellent distance vision with contact lenses and may
need only reading spectacles worn in addition to the contact lenses. Some aphakic patients will need multifocal
spectacles for optimum correction at distance and near.
11.4.40 With present cataract surgery techniques, wound healing and visual recovery are rapid and an eye
may be ready for contact lens fitting six to eight weeks after surgery. Proper contact lens fitting procedures and
appropriate follow-up examinations by a qualified vision care specialist are particularly important in aphakic
contact lens wearers. As with ordinary contact lens wearers, the aphakic applicant must demonstrate
satisfactory adaptation to the contact lenses before being considered for aviation duties.
11.4.41 Individuals who are aphakic in one eye, who use a contact lens in that eye and either spectacles
or no correction in the other eye will not generally be able to wear spectacle correction for both eyes because
of the large anisometropia. Such individuals should have a spare contact lens and a spare set of spectacles
available when exercising the privileges of their licence.
Intraocular lens correction of aphakia
11.4.42 The condition in which an artificial lens is placed inside the eye after cataract removal is called
pseudophakia. This is now the preferred method of treating cataracts in adults. The earliest intraocular lenses
were used in the 1940s. Since then there have been numerous modifications in lens design and manufacture
and in the surgical techniques for inserting these lenses. Usually the preferred lenses are placed behind the iris
within the crystalline lens capsule after removal of the cataractous cortex and nuclear material. These posterior
chamber intraocular lenses provide the best optical correction possible, and many patients have good distance
vision without additional correction. Most patients who have intraocular lens implants do need spectacles,
either reading spectacles or multifocals to achieve the best correction at distance and near. Multifocal
intraocular lenses are available but visual results with these lenses are less satisfactory than with single vision
intraocular lenses. Only single vision intraocular lenses are considered suitable for use in the aviation
environment.
Part III. Medical Assessment
Chapter 11. Ophthalmology III-11-31
11.4.43 The success rate for cataract surgery with intraocular lens implantation is excellent, and the newer
techniques using foldable lenses allow use of small incisions and no sutures so that surgically induced
astigmatism is reduced and visual recovery is rapid. Many patients see well the day after their surgery, and
most will have stable refraction six to eight weeks later.
11.4.44 The usual surgical complications which can occur following any operation that involves opening
the eye are seen in intraocular lens surgery but their incidence is considerably less than with the older cataract
surgery techniques. One of the most frequent problems following present day cataract surgery is opacification
of the posterior part of the crystalline lens capsule which may occur weeks to years after the surgery. This
results in reduction of vision but is usually easily treated by capsulotomy using a YAG5 laser. Such laser
treatment has a very low complication rate, is done in minutes with only topical anaesthesia and generally
results in rapid return of vision.
11.4.45 The high success rate for cataract surgery with intraocular lens implantation has resulted in
patients being offered surgery at an early stage in the development of their cataracts. Medical examiners will
see increasing numbers of applicants who have had this surgery.
Refractive surgery
11.4.46 Surgical correction of refractive errors is increasing dramatically. The aim is generally to allow the
patient to do away with spectacles or contact lenses. However, refractive surgery is now widely used to correct
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Manual of Civil Aviation Medicine 2(50)
