The Royal College of Ophthalmologists' National Ophthalmology Database Study of cataract surgery: report 2, relationships of axial length with ocular copathology, preoperative visual acuity, and posterior capsule rupture

Abstract

Purpose: To describe the relationships of axial length with ocular copathology, preoperative visual acuity, and posterior capsule rupture rates in patients undergoing cataract surgery.DesignThe Royal College of Ophthalmologists' National Ophthalmology Database (NOD) study.

Methods: Anonymised data on 180 114 eyes from 127 685 patients undergoing cataract surgery between August 2006 and November 2010 were collected prospectively from 28 sites. Data parameters included: demographics, biometry, ocular copathology, visual acuity measurements, and surgical complications including posterior capsule rupture, or vitreous loss or both (PCR).

Results: Consultant surgeons performed a higher proportion of operations on eyes whose axial length were at the extremes. Glaucoma and age related macular degeneration were more common in eyes with shorter axial lengths, whilst previous vitrectomy was associated with longer axial lengths. Eyes with brunescent or white cataracts or amblyopia were more common at both axial length extremes. Preoperative visual acuities were similar for eyes with axial length measurements up to approximately 28 mm and worse for eyes with longer axial length measurements. PCR rates showed little change with axial length (overall mean 1.95%, 95% CI: 1.89 to 2.01%), except for a borderline increase in eyes with axial length <20.0 mm where rates were 3.6% (95% CI: 2.0 to 6.3%). The likelihood of PCR in eyes with axial length <20.0 mm was 1.88 times higher than those of ≥20.0 mm (P=0.0373).

Conclusion: Rates of ocular comorbidities vary by axial length. PCR rates in eyes with very short or long axial lengths were lower than expected.

Figure 1

(a) The proportion of operations performed by each grade of surgeon according to baseline axial length. Consultant surgeons performed 105 078 operations, independent non-consultant surgeons 56 341 operations and trainee surgeons 18 634 operations. The axial length measurements were categorised into 1-mm increments except for measurements of <20 mm and ≥32 mm. (b) Box and whisker plots of preoperative visual acuity according to baseline axial length. The axial length measurements were categorised into 1 mm increments except for measurements of <20 mm and ≥32 mm. CF=Count fingers, HM, hand movements, PL, perception of light, NPL, no perception of light. The marks above the whiskers represent outlying values. (c) Posterior capsule rupture (PCR) rates with 95% confidence intervals by axial length (mm). The axial length measurements were categorised into 1 mm increments except for measurements of <20 mm and ≥30 mm.

Figure 2

(a) The proportion of eyes with either of age-related macular degeneration, diabetic retinopathy or other macular pathology according to baseline axial length. (b) The proportion of eyes with either of glaucoma or uveitis/synaechiae according to baseline axial length. (c) The proportion of eyes with either of amblyopia, brunescent/white cataract or previous vitrectomy surgery according to baseline axial length. For all, the axial length measurements were categorised into 1 mm increments except for measurements of <20 mm and ≥32 mm.