March 2018

CATARACT

Presentation spotlight
Managing eyes with long axial lengths


by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer




Figures 1A and 1B: As the phaco tip is withdrawn from the anterior chamber, air is injected through the paracentesis
(A) in order to keep the chamber formed and prevent collapse of the chamber with anterior movement of the vitreous body (B).


Figure 2A: Posterior displacement of lens and iris and sudden pupillary dilation right after the phaco tip was inserted in the anterior chamber

Figure 2B: The pupillary block is reverted by pressing down the anterior capsular leaflet with the second hand instrument.
Source: Daniel Badoza, MD

Challenges of cataract surgery in long eyes

Highly myopic eyes require special care when being considered for cataract surgery. Although there is no real consensus on the axial length that constitutes a “long eye,” most eye doctors would want to pay careful attention to eyes approaching 30 mm in axial length. Cataract surgeons need to be aware of the challenges associated with long eyes before, during, and after surgery. Speaking on long eye cataract surgery at the XXXV Congress of the ESCRS, Daniel Badoza, MD, medical director, Instituto de la Visión, Buenos Aires, Argentina, shared his pearls.

Preoperative pearls

One of the first challenges in long eyes in need of cataract surgery is obtaining a reliable measurement of axial length, which is ultimately essential for IOL power calculations. Axial length is hard to measure accurately in long eyes. Consequently, postoperative refractive error is one of the major complications in highly myopic eyes. “In patients with long eyes, we focus primarily on the biometry, IOL power calculations, and the right formula,” Dr. Badoza said. “When we perform an axial length measurement, we usually find posterior staphylomata, which are a source of error. They are common and we spot them with ultrasound biometry, using either contact or immersion techniques. Staphylomata can cause inaccurate biometry outcomes. Optical biometers are our best option for good measurements. We think they are mandatory in these eyes. Ultrasound imaging can help us to visualize a posterior staphyloma. However, even with an expert operator performing ultrasound biometry, we can end up with a 2-mm range in axial length results, which will cause problems in the estimation of the IOL power.”
The classic IOL power calculation formulas have a tendency toward hyperopic error in long eyes. Although the SRK/T formula is widely used, Dr. Badoza thinks it is imprecise. His preferences are the Olsen, Haigis, and Barrett formulas for higher accuracy, as they consider the anterior chamber depth (ACD) in the estimation of the effective lens position (ELP). Many IOL power calculations in patients with long eyes will result in a minus diopter IOL. To prevent postoperative refractive surprises due to the different architecture of the optic, the surgeon must use specific A-constants for these lenses.

Intraoperative pearls

Considerations intraoperatively begin with choosing the safest form of anesthesia. Dr. Badoza considers intracameral anesthesia best for these cases, as it is safer than retrobulbar or peribulbar, which have been associated with the risk of globe perforation in long eyes. Intracameral anesthesia would also reduce the patient’s discomfort in case a fluctuation in ACD occurs.
Long eyes are at an increased risk for lens-iris diaphragm retropulsion syndrome (LIDRS), characterized by adhesions between the iris and anterior capsule rim along 360 degrees. Dr. Badoza explained that LIDRS tends to appear just after the infusion starts intraoperatively, producing reverse pupillary block, pupil dilation, deepening of the anterior chamber, posterior bowing of the iris, and patient discomfort. Regarding the management of LIDRS, the surgeon can learn to mechanically break the iridocapsular block to restore normal chamber depth and relieve patient discomfort.1
“What you usually see is right after you introduce the phaco tip, there is a sudden dilatation of the pupil and a deepening of the AC,” Dr. Badoza. “You can use your second hand instrument to softly push back the capsule rim to return the diaphragm to its normal position and start phacoemulsification comfortably. Also, the syndrome can often appear when introducing the irrigation/aspiration tip. You see a wide and abrupt dilation of the pupil along with other classic symptoms. By carefully pushing back the capsule with the irrigation/aspiration tip, which is made of soft silicone, you reverse the block and can start the cortical cleanup.”

Postoperative pearls

Long eyes have the same postoperative issues as eyes with smaller axial lengths, such as cystoid macular edema, IOL miscalculation, retinal detachment, endophthalmitis/TASS, and endothelial decompensation.
The case for retinal detachment being a major concern in highly myopic eyes is well documented. According to a study on the risk of retinal detachment in eyes that underwent cataract surgery from the Danish National Patient registry, phacoemulsification increased retinal detachment 4.23 times in the cataract population as a whole, including short, normal, and long eyes.2 If phacoemulsification increases the overall risk of retinal detachment, as this study suggests, it poses a particular risk in long eyes, according to Dr. Badoza. Risk factors for retinal detachment are young age, male gender, and long axial length.
A retrospective consecutive interventional study found the incidence of retinal detachment after coaxial phacoemulsification in 439 eyes of 274 highly myopic patients to be 2.7%. The mean axial length in the study was 28 mm. The investigators reported a trend toward an increased incidence and risk of retinal detachment in patients younger than 50 years.3 Another retrospective medical chart review of 2,356 eyes in 1,519 consecutive patients with an axial length greater than 27 mm who had phacoemulsification with IOL implantation revealed a postoperative retinal detachment of 1.5–2.2%.4 However, the absence of control groups matched for age, sex, and myopia preclude these studies from elucidating the exact influence of phacoemulsification as a risk factor for retinal detachment in eyes more than 30 mm in axial length. A study of 453 emmetropic eyes of 453 patients that had phacoemulsification with IOL implantation showed the occurrence of posterior vitreous detachment (PVD) as associated with the reduction of volume occupied by the removal of the lens. The study suggested that the onset of postoperative PVD should be considered an important risk factor for the development of retinal detachment after cataract surgery, especially in eyes with lattice areas.5

Prevention

“To assure the prevention of pseudophakic retinal detachment in very long eyes, it is important to assess the indications for surgery and intraoperative prophylaxis,” Dr. Badoza said. “Patients up to 55 years of age with a clear lens and satisfactory BCVA are questioned about contact lens tolerance. If they can wear contact lenses, we prefer to defer surgery. If they are contact lens intolerant, however, then we consider posterior chamber phakic IOL implantation. Preoperatively, it is very important to give patients a detailed explanation about the pros and cons of this indication. Intraoperatively, to prevent severe or abrupt AC decompressions that would provoke vitreous traction and PVD, we need to keep the AC stable. To achieve that, we try to decrease the infusion bottle height before introduction or withdrawal of the infusion. We set slow phacodynamic parameters and perform phacoemulsification through the smallest incision our machine is able to work with, a 1.8 mm primary incision. After emulsifying the nucleus, we inject air or balanced salt solution through the paracentesis while withdrawing the phaco tip to prevent the anterior chamber from flattening. The same care should be taken after cortical cleanup; instead of air, we inject OVD while removing the I/A tip before implantation of the IOL.”

References

1. Cionni RJ, et al. Management of lens-iris diaphragm retropulsion syndrome during phacoemulsification. J Cataract Refract Surg. 2004;30:953–6.
2. Bjerrum SS, et al. Risk of pseudophakic retinal detachment in 202,226 patients using the fellow nonoperated eye as reference. Ophthalmology. 2013;120:2573–9.
3. Alio JL, et al. The risk of retinal detachment in high myopia after small incision coaxial phacoemulsification. Am J Ophthalmol. 2007;144:93–98.
4. Neuhann IM, et al. Retinal detachment after phacoemulsification in high myopia: analysis of 2356 cases. J Cataract Refract Surg. 2008;34:1644–57.
5. Ripandelli G, et al. Posterior vitreous detachment and retinal detachment after cataract surgery. Ophthalmology. 2007;114: 692–7.

Editors’ note: Dr. Badoza has no financial interests related to his comments.

Contact information

Badoza
: dabadoza@gmail.com

Managing eyes with long axial lengths Managing eyes with long axial lengths
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