|Year : 2017 | Volume
| Issue : 2 | Page : 89-90
Commentary on aphakic correction in Barau Dikko Teaching Hospital, Kaduna, Nigeria
Michaeline A Isawumi
Department of Surgery, College of Health Sciences, Osun State University, Osogbo, Nigeria
|Date of Web Publication||30-Apr-2018|
Dr. Michaeline A Isawumi
College of Health Sciences, Osun State University, Oke Baale, PMB 4944, Osogbo
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Isawumi MA. Commentary on aphakic correction in Barau Dikko Teaching Hospital, Kaduna, Nigeria. Arch Med Surg 2017;2:89-90
Aphakia can be described as the absence of the crystalline lens in its anatomical position. This means that it may be completely absent usually following surgical extraction or due to a congenital absence as can occur in ectopia lentis. It may also be partially absent following a displacement from the central visual axis. This usually follows trauma be it intentional as occurs during couching or unintentional during accidents (physical, throws, blows, etc.).,
The effect of aphakia is a very high hypermetropia which causes poor vision if not corrected. Spectacles, contact lenses, intraocular lenses (IOL) (including foldable/multifocal lenses), and refractive surgeries are methods that can be used for correction. Use of aspheric lenses reduces the weight of aphakic spectacles except for its inability to be used in unilateral aphakia due to 33% image size magnification.
It is true that, in Nigeria, couching for cataract is still a problem because this method is commonly used by the poor and ignorant populace. Poor accessibility to eye-care facilities and cost of surgery also contribute to its patronage. Unfortunately, it is most often accompanied by poor outcome and undesirable complications., For these reasons, I do not agree with the statement that “a demonstrated modified couching by use of alpha-chymotrypsin to break the zonules and a frozen probe to dislocate the lens can have better results than a poor surgery.” This is an archaic method and can only suggest that visual impairment from aphakia will continue to be an issue in the elderly until when standard cataract surgery with IOL implantation is available to all persons in need. Studies have also shown that IOL is cheaper than contact lenses (CTL) for rehabilitation. It is also more convenient than wearing glasses.
Modern methods of visual rehabilitation of aphakia need to be encouraged through health education and showing convincing evidence of good visual outcomes to the cataract-blind relations and caregivers. There are different types of CTLs that can be used. These range from hard contact lenses which are rigid and gas permeable, usually used for uniocular aphakia. This is the only thick type of CTL that is gas permeable. Extended wear CTL, which is worn for about 1 week before removal, is also aerated but can be complicated by infections in the absence of proper care. However, the types of CTL made of polymethyl methacrylate (PMMA) are those at risk of not being aerated.
Modern designs of IOLs such as open-loop anterior chamber IOLs, scleral sutured posterior chamber (PC) IOLs, and iris-sutured PC IOLs are considered safe and effective in correcting aphakia in eyes without capsular support, particularly in children., Iris claw retropupillary fixated aphakic IOL implantation has also been used for traumatic aphakia. To this end, secondary IOL implantation should be the way forward, particularly in a tertiary eye center, in Sub-Saharan Africa presently. For best practices, ultrasound biomicroscopy should be used to assess the anterior segment structures and status so that the type of IOL to be used can be determined. However, this is a luxury to come by for a developing country like Nigeria.
It would have been nice to see the types of visual rehabilitation offered. From the article, the impression of only glasses being used for rehabilitation was given. I would rather suggest that secondary IOL implantations are offered to these patients. The selection of the types should also be dependent on the patient's presentation. These options of secondary IOL implantations or glasses can then be offered to previous aphakics be it postsurgical, trauma, or couching during surgical outreaches or in the hospital as they are being planned for visual rehabilitation.
The last type of aphakic correction is through surgery. It is well documented and also known from principles of optics and physics that, in a very high myopic patient, removing the lens renders the refractive state near to emmetropia. Therefore, in a previously myopic patient who undergoes cataract extraction or couching to become aphakic, the vision will remain near normal.
Another alternative but more sophisticated method is keratorefractive surgery. Highly specialized equipment is used to alter the corneal curvature to achieve emmetropia and subsequent good vision. An example of this procedure is called epikeratophakia. However, the surgery outcome is more favorable in the young than the very aged patient because of endothelial cell loss that occurs with age.
This procedure is, however, very expensive. LASER surgery machines and the surgical expertise are also not readily available to all.
In conclusion, spectacles, PMMA IOL, and refractive surgeries are available for aphakic correction and visual rehabilitation.
I hereby express my gratitude to the editorial team for granting me the opportunity to write this commentary/Guest editorial.
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