Background/objectives

We provide global averages and standard deviations for ocular biometry-axial length (AL), corneal radius of curvature (CR), anterior chamber depth (ACD), lens thickness (LT), white to white (WTW), and central corneal thickness (CT). We hope a better understanding of normal and abnormal values will help clinicians gain further insight into their surgical outcomes, especially for off-target eyes.

Subjects/methods

We searched the MEDLINE database using keywords "axial length, corneal power, anterior chamber depth, lens thickness, white to white, and corneal thickness." We included studies that reported averages and standard deviations on eye biometry for at least 1300 eyes. Global weighted averages and standard deviations were calculated using the Cochrane method.

Results

Fourteen studies were included, originating from Asia (Japan, Singapore, Myanmar, Iran, South Korea, China), Europe (Germany, United Kingdom, Portugal), Australia, and North America (United States). Global ocular biometry metrics were: AL-23.49 mm ± 1.35 mm, CR-7.69 mm ± 0.28 mm, ACD-3.10 mm ± 0.47 mm, WTW-11.80 mm ± 0.42 mm, LT-4.37 mm ± 0.43 mm, and CT-544 μm ± 38 μm. Total eyes per value ranged from 19,538 to 90,814.

Conclusions

We report global ocular biometry averages and standard deviations. No eyes were from studies in Africa or South America, highlighting the need to publish eye biometry data from these continents. We hope that promoting a deeper understanding of biometry values will help clinicians gain insight into surgical outcomes and drive innovations in lens calculations.

We report a case of a child with secondary open-angle glaucoma who developed 6.5 diopters (D) of corneal flattening upon the addition of Rhopressa (0.02% netarsudil dimesylate solution) eye drops to a preexisting treatment regimen of timolol and latanoprost. This change in corneal power reversed after netarsudil, a rho-kinase inhibitor, was discontinued and replaced with Vyzulta (0.024% latanoprostene bunod ophthalmic solution). The 4-year-old female patient presented with bilateral secondary open-angle glaucoma from Paired Box 6 (PAX6)-related aniridia, aphakia, and persistent fetal vasculature. She was started on netarsudil to treat elevated intraocular pressure (IOP) in her right eye, which was not adequately controlled by latanoprost and timolol. Over 4 months, she developed 6.5D of corneal flattening in her right eye. Netarsudil was stopped and the corneal flattening reversed. There is evidence to support the ability of rho kinase inhibitors to increase the healing of the corneal endothelium in addition to their intended IOP-lowering effects. Rho kinase inhibitors may increase cell proliferation and adhesion within the corneal endothelium, hence decreasing apoptosis and promoting cell preservation. If there was an excess of cell proliferation; however, this might induce stromal cells to abnormally secrete enzymes or proteins, such as TGFβ-induced proteins. This could result in corneal fibrosis, thereby flattening the cornea. Further investigation is required to explore this phenomenon and elucidate its mechanism of action. Corneal flattening may be considered as a potential side effect of the use of netarsudil, particularly in young pediatric patients.