Tanu Sharma, Bachelor of Optometry

Fellow Optometrist, Dr. Shroff’s Charity Eye Hospital, New Delhi

Glaucoma is a group of disorders characterized by progressive optic neuropathy in which structural changes to optic nerve head (ONH) and peripapillary retina are associated with characteristic visual field (VF) defects. These functional deficits correspond to the anatomic distribution of the retinal nerve fibre layer (RNFL), which can affect our daily lifestyles.⁽¹⁾

This article is all about dispensing spectacles in glaucoma patients and reducing the problem that they face in their activities of daily living. The important part of dispensing is to ensure that the patient is dispensed with an optical correction that provides maximum optical performance, functionality, ‘wearing comfort’, and is always cosmetically pleasing to the wearer. To achieve all these dispensing practitioners will require comprehensive knowledge about the product as well as disease and practical dispensing experience.

When we are talking about visual difficulties of a glaucoma patient, field loss is a common complaint along with glare, halos, and reduced contrast sensitivity.⁽²⁾

‘Thera specs’ outdoor lenses can be a great option for people with glaucoma who find that wearing normal sunglasses outside does not provide enough protection against bright light and glares. Thera specs indoors and outdoors glasses are 100% UVA & UVB blocking.⁽³⁾ Another spectacle which we use for patients complaining of glare, light sensitivity, light, and dark adaptation problems are:

• Polarized glasses; minimize the reflected glare
• Mirror coating lenses; reduce the amount of visible light entering the eye
• Photochromic/transition lenses; that automatically darken when exposed to bright light and becomes lighter in lower lighting conditions.

We are aware that patients with peripheral field loss do not compensate for peripheral vision scanning around a wider area in front of them. To solve this problem, we advised high power prism glasses in peripheral lenses that widen the peripheral field more than 15 degrees to the area of blindness. As glasses with Fresnel prism power, bi-part and reflective prism are effective and increases 15 deg. field of area.⁽⁴⁾

As one study showed that even after the MIOL (Multifocal Intraocular Lens) implanted in patients with glaucoma have higher glare problems and need glasses for near work,⁽⁵⁾ so in this case, we always advise patients to use separate glasses for near and distance work with blue cut and  ARC (Anti-Reflection Coating) under the good illumination to enhance the contrast. Since PAL has a limited field of view for tasks, and glaucoma patients also have field loss and low contrast. Thus, Progressive addition lenses (PAL) or multifocal are not suitable for glaucoma. For early cases of visual field loss bifocal especially executive or D-bifocal are a good option for presbyopia correction.

Another major part is dispensing. The common optical errors resulting from a poorly fitting spectacle frame include changes to lens effectiveness, a reduction in the useful field of view, the introduction of oblique distortion, and prismatic error. Pantoscopic tilt can also enhance near field while keeping in mind that incorrect Pantoscopic tilt will lead to oblique aberrational error. Spectacle magnification can help to expand the visual field by reducing image size. In that case, slightly over myopic correction or vertical cylinder incorporation can help glaucoma patients.

At dispensing, the practitioner must always communicate with the patient to identify the most appropriate lens and frame option and advise them of the optical and functional limitations. If the disease is diagnosed in early stages, with proper eyeglasses according to the needs can give a positive impact on a patient’s daily lifestyle.

References

1. Cohen, L. P., & Pasquale, L. R. (2014). Clinical characteristics and current treatment of glaucoma. Cold Spring Harbor perspectives in medicine, 4(6), a017236.
2. Dubey, S., Bedi, H., Bedi, M., Matah, P., Sahu, J., Mukherjee, S., & Chauhan, L. (2020). Impact of Visual Impairment on the Wellbeing and Functional Disability of Patients with Glaucoma in India. Journal of current ophthalmology, 32(1), 14–18.
3. https://theraspecs.com/glaucoma-glasses-and-sunglasses/(2011).
4. Szlyk,J. P., Seiple, W., Laderman, D. J., Kelsch, R., Ho, K., & McMahon, T. (1998). Use of bioptic amorphic lenses to expand the visual field in patients with peripheral loss. Optometry and vision science: official publication of the American Academy of Optometry, 75(7), 518–524.
5. Sánchez-Sánchez, C., Rementería-Capelo, L. A., Puerto, B., López-Caballero, C., Morán, A., Sánchez-Pina, J. M., & Contreras, I. (2021). Visual Function and Patient Satisfaction with Multifocal Intraocular Lenses in Patients with Glaucoma and Dry Age-Related Macular Degeneration. Journal of ophthalmology, 2021, 9935983.