Cataract surgery tricky in small hyperopic eye with shallow anterior chamber
Cataract surgery in small hyperopic eyes can be challenging due to the constraints of working in a significantly smaller space.
These patients have short axial lengths and typically shallow anterior chambers. They also tend to not dilate as well so we have to operate through a smaller pupil. And in this case, the patient was also monocular, so there was added stress for both the patient and surgeon because the stakes were so high.
Source: Uday Devgan, MD
Consultation and evaluation
At the consultation, careful assessment was done to evaluate the anterior chamber depth, pupil dilation and degree of cataract. When reviewing the biometry, axial lengths under 20 mm are considered nanophthalmic and often have zonulopathy. The IOL calculations are also less accurate in these eyes, and a slight difference in effective lens position can change the refraction significantly because the IOL power tends to be high. These patients are used to hyperopia, and even though it may seem counterintuitive, they tend to prefer to be left a little hyperopic instead of myopic. While I would choose –0.5 D over +0.5 D for my eyes, these patients would do the opposite.
When dealing with monocular patients, there is often a reluctance to have surgery, particularly if the first eye was lost due to surgical complications. While we do not want to pressure the patient to have surgery, delaying the surgery can result in a more difficult case. As the nuclear sclerosis continues to progress, the lens thickness can increase, which will further shallow the anterior chamber. This patient waited a few years until vision was insufficient for household tasks and then was mentally ready for cataract surgery.
Surgical technique
Topical anesthesia was selected so that after surgery the patient would be able to see immediately. The anesthesiologist administered intravenous sedation to help with the patient’s high level of anxiety.
The pupil dilated to about 4 mm with pharmacologic agents, and then injection of viscoelastic at the pupil margin was used to further push out the iris tissue, giving more mydriasis. I wanted to avoid the use of iris hooks and pupil expansion rings if possible because I find that iris stroma manipulation leads to more postoperative inflammation. Also, with a shallow anterior chamber, it is more difficult to insert a pupil expansion ring. Certainly, if the surgeon deems that using iris hooks would make the case safer in his/her hands, then please use them. The technique of pupil stretching could also be employed if needed.
The capsulorrhexis was created right at the pupil margin or slightly under the iris to achieve a 5 mm diameter (Figure 1). We wanted to avoid making a small capsulorrhexis because it would make nucleus removal more challenging. After hydrodissection, I elected to perform stop-and-chop for nucleus disassembly. While I typically prefer variations of phaco chop, the advantage of stop-and-chop is the ability to debulk the central nucleus. Also, by creating a wide groove, each nuclear half will be smaller, about 40% to 45% of nucleus volume; if a quick chop were performed, each half would be 50%. This allows more room to bring the nuclear halves up for further division with the chopper (Figure 2).
After the nucleus was removed, the irrigation and aspiration probe was used to clear the cortex from the capsular bag. The IOL was a higher dioptric power because of the patient’s small eye and preoperative hyperopia, and that means it was also thicker. This requires the surgeon either to enlarge to a slightly wider incision or to use the wound-assist technique to deliver the IOL into the eye. With the smaller degree of dilation, it was imperative that we ensure that the entire IOL was in the capsular bag with both haptics under the capsulorrhexis. If the IOL decenters after viscoelastic removal, then the surgeon should suspect inadvertent placement of one haptic in the sulcus. This should be addressed immediately because it can lead to problems such as chronic uveitis or even glaucoma.
Before removing the viscoelastic, I like to use the chopper to gently lift up the iris in all quadrants to visualize that the IOL is in good position and also to check for residual cortex at the capsular bag equator. In this case, there was a significant amount of retained cortex hidden under the iris in the nasal quadrant (Figure 3). The I&A probe was used to remove this and evacuate the viscoelastic. The incisions were then hydrated with balanced salt solution. The eye was medicated with intracameral moxifloxacin for endophthalmitis prophylaxis, and the incisions were checked again for integrity.
This patient achieved an excellent postoperative result of close to plano with the monofocal IOL. Both the surgeon and the patient were pleased and relieved.
A video of this can be found at https://cataractcoach.com/2025/01/08/2438-small-pupil-shallow-ac-stop-chop/.
- For more information:
- Uday Devgan, MD, in private practice at Devgan Eye Surgery and a partner at Specialty Surgical Center in Beverly Hills, California, can be reached at devgan@gmail.com; website: www.CataractCoach.com.
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