Background information on the main source of funding for each eye unit was also collected as this affects procurement of new equipment as well as maintenance and repair. Overall, half Encouragingly, This was true in all regions surveyed and across the full range of equipment covered in the survey.
Without biometry, surgeons cannot select the most appropriate intraocular lens IOL power and patients may need optical correction after surgery.
Jeremy Clark, MD
When considering training institutions separately, we found that If the results can be assumed to be representative of the different regions, it is cause for concern that so few cataract surgeons in Africa, the Eastern Mediterranean region, and the Western Pacific region have the opportunity to be trained in routine biometry. Over half of the eye care institutions responding from Africa and South-East Asia had no visual field analysers; this highlights the need to strengthen quality glaucoma management in these regions.
Figure 3 highlights the challenges faced in the government sector the main health service provider in many countries compared to the NGO and private sectors. In all instances, more government eye units had equipment that did not work. On average, easily manageable or preventable causes were responsible for more than a third of the equipment that had stopped working Figure 4. In one extreme case, slit lamps were not working for over 15 years.
The key trend noted was that equipment not working for longer than a year was predominately a problem within government hospitals. One of the common reasons that equipment did not work for long periods of time was that the model was too old and that spare parts were not available; this was true for slit lamps, retinoscopes, indirect and direct ophthalmoscopes, and visual field analysers in particular.
Furthermore, there was no designated person to take responsibility for the equipment that did not work. This could help to explain the delays in arranging for repairs. We need somebody who can [teach] them ophthalmic instrument maintenance. Lack of funding, especially in government settings, was raised as a major barrier in all regions.
Some eye units have had to cancel or reschedule clinics and operations when their equipment broke down.
For both outreach services and those at the clinic, the inconvenience to patients is great, particularly in rural areas where patients often have to travel long distances. Long-term or repeated cancellations result in disappointment and loss of trust. This can damage the reputation of the eye care service and will have an impact on its ability to attract patients in future.
Delays and cancellations are frustrating for eye care staff and have an impact on their motivation; this will in turn diminish their ability to deliver high-volume, highquality services. As a result, retention of trained professionals in poorly equipped centres may become a challenge.
This could theoretically increase the effect of higher-order aberrations because of an increase in the pupil size. Just as the corneal intercept of the visual axis is used for centration of ablation in LASIK, we attempted to use the angle kappa measurement as an intraoperative guide to center a multifocal IOL. We marked the visual axis using the coaxially sighted light reflex.
Dr. Alison Chiu | Specialist Eye Surgeon Bondi Junction | Ophthalmologist Sydney, NSW
We marked the visual axis and the pupillary center on the cornea. Despite the inability to ensure perfect accuracy, we observed promising results with this technique. There are certain situations where, despite best attempts, a centered multifocal IOL in the bag may not be possible in a patient who wants a multifocal. In such a patient, it is possible to perform a glued IOL and to adjust the centration by adjusting the location of the scleral flaps, sclerotomies and the degree of tuck of individual haptics.
In other situations such as microspherophakia, our preferred practice is to do a lensectomy and implant a glued IOL, which, if it is multifocal, needs to be centered on its rings. It would also be ideal to combine this with ray optics and to be able to center the IOL ideally so that the light ray passes from fixation through the center of the rings to the fovea.
In the event of a posterior capsular rent, it is not advisable to place a multifocal IOL in the sulcus for fear of postoperative decentration.
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If in-the-bag multifocal IOL implantation is not possible, a glued multifocal IOL may be preferable, as the IOL is stable with no postoperative decentration occurring from its intraoperative positioning. In all these complicated situations as well as, more importantly, in the routine multifocal IOL patients, it is important to take the angle kappa into consideration for IOL centration.
Angle kappa may play important role in success of multifocal IOLs
Future advances might also include IOL customization to match the angle kappa of the patients, although postop capsular contraction and IOL rotation would be challenges to overcome. We also studied angle kappa in relation to visual satisfaction in multifocal patients and found photic phenomena to have an association with angle kappa.
Multifocal IOLs work on either a refractive or a diffractive principle and have either multifocal zones or steps. In an eye with a small angle kappa, the ray of light would be able to pass through the IOL center without disturbance, but in an eye with a large angle kappa, a fovea centric ray might hit on the edge of the ring, thus giving rise to edge glare effects Figure 4. A monofocal IOL in an eye with a large angle kappa would not cause as much visual disturbance as a decentered multifocal IOL because of the lack of steps or rings on its surface.
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To conclude, we propose that it is important to focus more research on the association between angle kappa and multifocal IOLs. It may be important to consider angle kappa for all prospective multifocal IOL patients and to avoid multifocal implantation in patients with large angle kappa until advances make accurate centering of IOLs possible.
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Amar Agarwal Angles of the eye have, of late, received a renewed interest secondary to the significant role they play in refractive surgery. Figure 1. Angle kappa is the angle between the visual axis and the pupillary axis. Figure 2.
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