Cataract: YES Connect
Spring 2024
by Ellen Stodola
Editorial Co-Director
Short eyes are often the most challenging for cataract surgeons. Preoperatively, lens selection can be tricky, as the effective lens position is hard to predict in these eyes. These patients are often hyperopic to start and may be less accepting of a myopic result. Intraoperatively, issues with effusions and iris prolapse can make a routine case very complicated. Even after surgery, patients may need to be monitored for chronic angle closure from peripheral anterior synechiae or may need to be treated for aqueous misdirection should it occur.
JoAnn Giaconi, MD, and Sahar Bedrood, MD, PhD, are both glaucoma specialists and cataract surgeons who have dealt with their fair share of short eyes. In this month’s YES Connect column, they review their approach to short eyes. They discuss their methods for lens selection and provide pearls on how to avoid complications like iris prolapse and effusions.
One final pearl: Do not underestimate how helpful relieving some posterior pressure at the start of cataract surgery can be. Placing a pars plana trocar and removing some vitreous will immediately deepen the anterior chamber, and the rest of the surgery will go routinely.
– Mitra Nejad, MD, YES Connect Editor
Performing cataract surgery in short eyes comes with certain challenges and considerations. Two surgeons discussed how to approach these patients, as well as certain formulas and surgical approaches that can help in these cases.
Sahar Bedrood, MD, PhD, and JoAnn Giaconi, MD, defined a short eye as one that is less than 22 mm in axial length. “Less than 21 mm is where I personally will start making some adjustments to technique. For others it is less than 20 mm,” Dr. Giaconi said.
Dr. Bedrood said that patients with an axial length of less than 22 mm typically are hyperopic and may have narrow angles.
“I perform intraocular pressure checks and gonioscopy to rule out angle closure, which would require IOP-lowering drops or more imminent cataract surgery for lens removal,” she said. “Accurate axial length measurements are key because we know that small deviations from the correct axial length in short eyes can lead to large refractive error. Therefore, I do measurements with both partial coherence interferometry (IOLMaster, Carl Zeiss Meditec) and optical low coherence reflectometry (Lenstar, Haag-Streit). This allows me to cross check the measurements for accuracy. I would also consider doing a UBM to measure scleral thickness, as we know that is a risk factor for choroidal effusions and possible malignant glaucoma following surgery.”
If the axial length is <18 mm or the sclera appears thickened and Dr. Bedrood notices a uveal effusion (high IOP and shallowing of chamber at the time of surgery), she said she anticipates the possibility of scleral windows at the time of surgery.
Dr. Bedrood said that a short eye might leave patients at a slightly higher risk for postop complications like iris prolapse, corneal edema, malignant glaucoma, and CME.
Dr. Giaconi said that she will let patients know that a short eye tends to have crowded anatomy and that it is at higher risk for certain complications, like iris prolapse, which can lead to transillumination defects postoperatively. It can also be more difficult to remove the lens, and therefore, there is a higher risk for corneal edema. “Predicting where the lens implant will end up in the eye is also more difficult, so hitting the refractive target is less certain,” she said.
Dr. Bedrood agreed that lens calculations may be different with these short eyes. “I make the patient aware that the lens calculations are made based on formulas that consider the dimensions of the eye,” Dr. Bedrood said. “Since the dimensions of their eyes fall in an ‘abnormal’ range, then we have some limitations with the formulas and a possibility of postoperative refractive error is possible. Over the last few years, however, we have had newer lens formulas developed to help reduce the chance of refractive error.”
Dr. Giaconi recommends newer IOL calculation formulas. “There are some studies showing the Kane formula as promising for short axial lengths,” she said. “I like the new [ESCRS] IOL calculator which shows multiple formulas of the newest generation and allows me to compare multiple formulas.”
Dr. Bedrood said that, in the past, the formulas that were suggested for use in short axial length eyes were the Haigis and Hoffer Q formulas. “There are newer formulas that we now implement into our practice,” she said, adding that the K6 formula and the Kane formula are multivariate formulas that have shown good success for obtaining targeted refractive outcomes in the shorter eyes.1
Short eyes are more difficult to operate in, Dr. Giaconi said. There can be more positive posterior pressure; the anterior chamber is often shallow; the capsulorhexis can have a tendency to run out; and iris prolapse is more common, which can lead to iris damage.
“For shorter eyes, I will administer IV mannitol about an hour before surgery (20 grams), if the patient can tolerate it. This dehydrates the vitreous and removes positive posterior pressure,” Dr. Giaconi said. If mannitol isn’t safe, some people will use acetazolamide preoperatively, she said. If the AC is very shallow, a limited pars plana vitrectomy can be done. “If one isn’t comfortable doing this themselves, one can partner up with a retina surgeon to do it, especially if a retina surgeon operates on the same day as you in your operating rooms,” she said. “It takes them just a couple of minutes to complete and can significantly deepen the anterior chamber and make operating much easier.”
Dr. Bedrood said the initial surgical challenge with these eyes is the posterior pressure and the small space within the anterior chamber, which makes it challenging to maneuver instruments.
She also recommended using IV mannitol preoperatively to help decompress the vitreous and move the lens more posteriorly. “I also recommend femtosecond laser for the rhexis so that there is less potential for the cornea to be touched by instruments during the creation of the rhexis,” she said. “Other considerations include the possibility of iris prolapse, so I will have iris hooks on standby.”
About the physicians
Sahar Bedrood, MD, PhD
Glaucoma & Cataract Surgeon
Advanced Vision Care
Los Angeles, California
JoAnn Giaconi, MD
Stein Eye Institute
University of California
Los Angeles, California
References
- Sandhu U, et al. Comparison of IOL calculation formulas for long and short axial length eyes. Invest. Ophthalmol Vis Sci. 2023;64(8):1203.
Relevant disclosures
Bedrood: Abbvie, Glaukos, Thea Laboratories, Ocular Therapeutix, BVI, Elios Vision
Giaconi: LightTouch
Contact
Bedrood: saharbedrood@gmail.com
Giaconi: giaconi@jsei.ucla.edu
