Optical Biometry Derived Axial Length Measurements Following Intravitreal Anti-Vascular Endothelial Growth Factor Treatment for Macular Edema

Swept-source OCT reduces the risk of axial length measurement errors in eyes with cataract and epiretinal membranes

AIMS

To compare the biometric data from partial coherence interferometry (PCI) and swept-source OCT (SS-OCT) in patients with age-related cataract and epiretinal membrane (ERM): ERM, ERM with foveoschisis and macular pseudohole.

METHODS

49 eyes of 49 subjects including 36 ERM, 9 ERM foveoschisis and 4 macular pseudohole were analysed to evaluate the axial length (AL) measurements and the presence of AL measurement errors, defined basing on the shape of the biometric output graphs and on the concordance of AL values between instruments. Eyes with ERM were divided in four stages according to OCT features (i.e. presence/absence of the foveal pit, presence of ectopic inner foveal layers, disrupted retinal layers).

RESULTS

The devices provided similar mean AL measurements in all subgroups, with differences <0.1 mm in 41/49 cases (83.6%). AL measurement errors were observed in ERM stages 3 and 4, characterized by ectopic inner foveal layers, and were significantly more frequent with the PCI (8/17, 47%) as compared with the SS-OCT device (2/17, 12%), p = 0.02. The refractive prediction error in cases with AL measurement errors was significantly greater using the PCI compared to the SS-OCT device (p<0.05).

CONCLUSION

Both devices provide reliable biometric data in the majority of patients and can be used in the preoperative assessment of patients with age-related cataract and ERM. In eyes with ectopic inner foveal layers, attention should be paid as AL measurement and refractive prediction errors may occur, more frequently with the PCI device.

Biometry in cataract surgery: a review of the current literature

PURPOSE OF REVIEW

To review the literature in 2017 and 2018 pertaining to biometry for cataract surgery and report pertinent findings.

RECENT FINDINGS

New devices using swept-source ocular coherence tomography can measure axial length in dense cataracts more frequently than common biometers. Computer-assisted registration may be superior to intraoperative aberrometry for toric intraocular lens (IOL) placement. Soft contact lenses may not require removal as long before biometry as previously thought. The Barrett Universal II IOL formula has been found to perform well at all axial lengths.

SUMMARY

New swept-source ocular coherence tomography biometers are more frequently successful at measuring axial length in dense cataracts which promises to improve refractive outcomes. Accuracy in toric IOL placement is likely to increase with improved devices. It may not be necessary to have patients remove soft contact lens any more than 2 days prior to biometry. The Barrett Universal II IOL formula may be used confidently for most eyes. Advancements acknowledged, purchasing new equipment will not be necessary for all surgeons.