Optometry Dx: Gone Without A Flash

Slideshow

  • Figure 1. This fundus image shows the patient after undergoing vitrectomy.

  • Figure 2. This anterior segment photo shows the patient’s nuclear cataract that rapidly formed 3 months later.

A 51-year-old woman presented with sudden loss of vision in the left eye for 1 day. Upon exam, her best corrected visual acuity (BCVA) was OD 20/20 and OS 20/200. She did not recall suddenly seeing light flashes or many floaters or spots in either eye in the recent past. Pinhole did not improve the VA in her left eye. Her medical history was unremarkable and she was taking no medications. Her pupils reacted normally in both eyes. Dilated indirect ophthalmoscopy revealed a 4+ vitreous hemorrhage in the left eye. The fundus details were not visible. She was seen by a retinal specialist the next day. Using B scan ultrasonography, the specialist found a flap tear in the superior nasal peripheral retina. With vitrectomy, the surgeon was able to remove most of the blood and laser treatment was then applied. Fundus imaging shows the break with the surrounding laser treatments a few days later (Figure 1). 

The peripheral nasal retina around the tear was attached. The pale laser scars had not yet become well attached to the retina by the retinal pigment epithelial (RPE) pigmentation, as this takes at least 7 to 10 days. No gas bubble was needed for this break as the macular area was not involved. Anterior segment imaging shows the nuclear cataract that rapidly formed 3 months later (Figure 2). The prescription in her left eye had increased by 3 diopters from the cataract. 

She later underwent cataract surgery with a standard intraocular lens (IOL) implant in the left eye, achieving vision of 20/20 OU with her original spectacle prescription (-5.00 OU). She was given progressive bifocal glasses with adds of +1.00 OD and +2.25 OS. She was subsequently fit to bifocal soft contact lenses with more power for the add in the left contact lens.

A small amount of blood resolves with time and will allow the clinician to easily locate the tear. If the exam is done early, the blood is generally located in the adjacent vitreous. A great amount of blood tends to...

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A small amount of blood resolves with time and will allow the clinician to easily locate the tear. If the exam is done early, the blood is generally located in the adjacent vitreous. A great amount of blood tends to obscure the fundus details and B scan ultrasound is needed. In a 2010 study, only 53.7% of tears were located with fundoscopy or ultrasound. The remaining 46.3% were located after the vitrectomy. Small tears were missed with ultrasound.1 

The Retinal Break and Vitrectomy

It is common knowledge that the vitreous gel has attachments to the peripheral retina and optic nerve. With age, the gel contracts and the vitreoretinal attachments are separated from the retina. If the peripheral retinal vitreoretinal attachments do not separate cleanly from the retina, a retinal break may take place with bleeding from the retinal vessels into the vitreous. A small amount of blood will resolve over time. A great deal of blood needs to be removed because it can cause problems that interfere with vision recovery. An early vitrectomy may be performed and the vitreous is replaced slowly as needed, with a balanced salt solution (BSS) that helps block oxygen from reaching the back of the lens. This may help slow the development of a nuclear cataract.2,3 Aqueous backflow from the ciliary body also quickly helps fill the posterior chamber. 

Nuclear Cataract Development

A vitrectomy is known to cause cataracts, primarily nuclear cataracts. Research demonstrates that post-vitrectomy patients in their 50s develop nuclear cataracts at an increased rate with each passing decade.2 The vitreous acts to block oxygen from reaching the back of the lens. When any part of the vitreous is removed, oxygen exposure to the lens increases and ages the lens.3 With aging, the lens becomes thicker and nucleus fibers become disorganized, firmer, and less transparent. Axial length is also associated with increased vitreous liquefaction and nuclear cataracts. The liquefaction of the vitreous facilitates the passage of oxygen from the retina to the back of the lens, aging the lens.4,5 

Keep in mind that normal vitreous liquefaction is found more in patients with longer axial lengths, and we can therefore speculate that patients with myopia are more likely to develop cataracts even sooner after a vitrectomy. 

Our patient developed a significant nuclear cataract 3 months after the vitrectomy. A posterior subcapsular cataract likely would have been present at 3 months if a gas bubble had been used for surgery to reattach the retina. The bubble initially expands and also may affect the posterior capsule, even with limited head positions.

Matthew Garston, OD, is an adjunct professor at the New England College of Optometry and was a senior staff optometrist in the medical department at MIT for 43 years.

References

1. Tan HS, Mura M, Biji HM. Early vitrectomy for vitreous hemorrhage associated with retinal tears. Am J Ophthalmol. 2010;150(4):529-533. doi:10.1016/j.ajo.2010.04.005

2. Thompson JT. The role of patient age and intraocular gasses in cataract progression following vitrectomy for macular holes and epiretinal membranes. Trans Am Ophthalmol Soc. 2003;101:485-498. 

3. Holecamp NM, Shui YB, Beebe DC. Vitrectomy surgery increases oxygen exposure to the lens. Am J Ophthalmol. 2005;139(2):302-310. doi:1016/j.ajo.2004.09.046 

4. Harocopos GJ, Shui YB, McKinnon M, Holekamp NM, Gordon MO, Beebe DC. Importance of vitreous liquefaction in age related cataract. Invest Ophthalmol Vis Sci. 2004;45(1):77-85. doi:10.1167/iovs.03-0820 

5.  Holecamp NM, Harocopos GJ, Shui YB, Beebe DC. Myopia and axial length contribute to vitreous liquefaction and nuclear cataract. Arch Ophthalmol. 2008;126(5):744. doi:10.1001/archophth.126.5.744-a