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Seeing into the Future of Presbyopia

July 2, 2017



Asyvia Powell - Medical Student1, Norberto Mancera MD2 and Hershel R Patel MS MD2


1MD Candidate, University of South Florida Morsani College of Medicine, Class of 2019
2Department of Ophthalmology, University of South Florida Morsani College of Medicine




Presbyopia is a condition of decreased accommodative amplitude, the ability of the eye to adjust and focus on a near object, that usually affects people over the age of 40. Typical signs and symptoms of presbyopia include gradual difficulty reading fine print especially at close range. Patients may also present with headaches, delays in focusing on near and distant objects, squinting, need for a brighter light while reading, double vision, and fatigue. Presbyopia can also be associated with environmental factors, systemic diseases (ex. diabetes, Multiple Sclerosis), or drug induced (ex. antidepressants, diuretics) according to the American Optometric Association.1

More than 1 billion people are affected by this problem with the prevalence ranging from 43% to 83%.2 Presbyopia is one of the leading causes of disability and the burden is greatest among vulnerable populations with the most contributing factors for onset of disease being sex, race, ethnicity, climate, rurality, and geographic location.3 There are theories as to the pathological reason why presbyopia occurs but there is no consensus on the exact reason.4

Diagnosis

Visual acuity testing is fundamental for diagnosis of presbyopia. Patients with uncorrected or undercorrected myopia are less likely to have complications with near tasks unlike hyperopia patients who would have increased complications with near tasks.1

Management

Distance refraction is important in the management of presbyopia. The optical correction for presbyopia is the sum of refractive correction for distance plus the power of the near addition.1 There are many types of treatment options for presbyopia including spectacles, contact lens, and surgery.

Spectacles and contact lens treatment

Spectacles come in various types from readers, bifocals, multifocals or progressives. Readers work by being placed 25mm in front of the eye's center of rotation and eye movements direct the visual axis through different areas of the lens.5 If there are more than one lens power in the spectacle such as the case of bifocal, multifocals or progressives this would allow the patient to actively select to see at specific visual distances.5 A disadvantage to the use of bifocals or progressives is the additional head or body movements that may be needed to orient the correct area of the lens to the visual axis. Complications with all bifocal, multifocal, or progressive spectacles are image jumping and distortion of peripheral images.5

There are alternatives to wearing spectacles in correcting for presbyopia.

An alternative to spectacles is contact lenses. One option is to use contact lenses to correct for distance, if needed, and use readers for near vision. Another option is to create monovision in which one eye is corrected for distance and the other eye is corrected for near vision. A third option is to utilize bi-focal or multi-focal contact lenses. The disadvantage of monovision is that suppression is supposed to allow binocular acuity to match the better eye but in some patients this is not possible.5 Other issues with monovision are loss of stereoacuity, increased risk of tripping, and problems with intermediate vision with higher add power.5

Surgical treatment

Surgical monovision is similar in concept to the previously mentioned monovision created with contact lenses. The difference is this monovision is produced surgically either via Laser assisted in situ keratomileusis (LASIK) or post cataract surgery with an monofocal intraocular lens.4 Monovision allows patients the opportunity to be spectacle free. If patients cannot adjust laser vision correction can be performed to make bilateral distance correction.4

Conductive keratoplasty is another surgical option for presbyopia. Conductive keratoplasty was FDA approved in 2004 for the treatment of hyperopia and uses radio waves to steepen the cornea by causing a permanent change to the architecture of the collagen of the cornea leading to an increase in refractive power.4 Post-surgical complications of conductive keratoplasty include halos or glares which can occur shortly after surgery and over time regression of surgically corrected near vision has been reported with some patients regressing to their pre-operative refractive state. 4,6

A less invasive surgical treatment for presbyopia are corneal inlay placement. Corneal inlays are reversible implants that utilize different optical principles as a mechanism for increasing depth of focus.4 The advantage of a corneal inlay is that they are reversible, minimally invasive, repeatable, and provide increased near vision with little loss of distance vision.4 Currently the only FDA approved inlay utilizes pinholes to increase depth of focus. It is placed in a pocket created in the non-dominant eye and has shown to be well tolerated.4,7 The opacity of the Karma inlay may impede future cataract or retinal surgeries because of decreased visibility into the eye.4 Since near vision is only achieved in one eye patients must be able to tolerate monovision. Post-insertion complications include halos, glares, increase night glare, neuroadaptive issues, and possible permanent corneal alterations.4,6,7 Patients may later need reading glasses if their accommodative needs surpass their inlay.4

Cataract surgery or clear lens extraction allows for another surgical option for the treatment of presbyopia by utilization of intraocular lenses. There are two different types of intraocular lenses multifocal or accommodating intraocular lens. Multifocal intraocular lenses are designed with concentric rings in the lens that focuses light from two different distances which allows patients to see objects at near and far distances.4 Multifocal intraocular lenses are not apt in patients with high degrees of astigmatism or other forms of corneal dystrophies or degenerations.4,6,8 A toric multifocal intraocular lens has been recently FDA approved which should allow for an increase in patients able to receive a multifocal lens. Complications of multifocal intraocular lenses are glares, halos, potential limitations at certain distances, limitations in certain lighting situations, and decreased contrast sensitivity.4,6,8

Accommodating intraocular lenses are designed to change the refractive power by contractions of the ciliary muscle, changing vitreous pressure, or reducing the diameter of the capsular bag.9 Unlike the multifocal intraocular lenses, the accommodating lenses have a single point of focus.9 An advantage of accommodating intraocular lenses are more patients are candidates for them compared to multifocal intraocular lenses and patients experience less glare, halos, and less decrease in contrast sensitivity compared to multifocal intraocular lenses.4,6,9 A disadvantage of accommodating intraocular lenses is their variable ability to accommodate and visualize near objects.4,6,9

Currently there is no perfect option of surgical correction of presbyopia. All previously mentioned options require patients to adjust or compromise their visual expectation compared to their previous pre-presbyopia state. There is continual research being performed on different types of surgical options for the treatment of presbyopia. Some of the surgical treatments currently being researched for future applications of presbyopia treatment include different types of corneal inlays, scleral implants, and femtosecond laser procedures.

References

1. American Optometry Association.(2010). Guideline synthesis: Optometry clinical practice guideline care of the patient with presbyopia. In: American Optometry Association Clinical Guideline[website]. St. Louis, MO. Available from: http://www.aoa.org/optometrists/tools-and-resources/clinical-care-publications/clinical-practice-guidelines?sso=y

2. Frick, K. D., Joy, S. M., Wilson, D. A., Naidoo, K. S., & Holden, B. A. (2015). The global burden of potential productivity loss from uncorrected presbyopia. Ophthalmology, 122(8), 1706-1710. doi:http://dx.doi.org.ezproxy.hsc.usf.edu/10.1016/j.ophtha.2015.04.014

3. Hickenbotham, A., Roorda, A., Steinmaus, C., & Glasser, A. (2012). Meta-analysis of sex differences in presbyopia. Investigative Ophthalmology & Visual Science, 53(6), 3215-3220. doi:10.1167/iovs.12-9791

4. . Davidson, R. S., Dhaliwal, D., Hamilton, D. R., Jackson, M., Patterson, L., Stonecipher, K., . . . Donaldson, K. (2016). Surgical correction of presbyopia. Journal of Cataract & Refractive Surgery, 42(6), 920-930. doi:http://dx.doi.org.ezproxy.hsc.usf.edu/10.1016/j.jcrs.2016.05.003

5. . Charman, W. N. (2014). Developments in the correction of presbyopia I: Spectacle and contact lenses. Ophthalmic and Physiological Optics, 34(1), 8-29. doi:10.1111/opo.12091

6. . Gil-Cazorla, R., Shah, S., & Naroo, S. A. (2016). A review of the surgical options for the correction of presbyopia. British Journal of Ophthalmology, 100(1), 62-70. doi:10.1136/bjophthalmol-2015-306663

7. Naroo, S. A., & Bilkhu, P. S. (2016). Clinical utility of the KAMRA corneal inlay. Clinical Ophthalmology (Auckland, N.Z.), 10, 913-919. doi:10.2147/OPTH.S89132

8. Greenwood, M., Bafna, S., & Thompson, V. (2016). Surgical correction of presbyopia: Lenticular, corneal, and scleral approaches. International Ophthalmology Clinics, 56(3)

9. Pepose, J. S., Burke, J., & Qazi, M. A. (2017). Benefits and barriers of accommodating intraocular lenses. Current Opinion in Ophthalmology, 28(1), 3-8. doi:10.1097/ICU.0000000000000323

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