Changes in axial length after vitrectomy for rhegmatogenous retinal detachment combined with choroidal detachment

INTRODUCTION

As advances have emerged in microsurgical instrumentation on small-gauge pars plana vitrectomy (PPV),phacovitrectomy surgery has, therefore, become a popular procedure in treating rhegmatogenous retinal detachment(RRD)

. Axial length (AL) and keratometric value measured before surgery are greatly important in calculating the intraocular lens (IOL) power in RRD patients undergoing combined phacovitrectomy.

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Rhegmatogenous retinal detachment combined with choroidal detachment (RRD-CD) is a kind of RRD with a specific low IOP character and is reported to affect 8.6%-19.2% of the RRD population in China

. The need for cataract extraction during PPV is present in RRD-CD cases due to difficulties in viewing the fundus or dealing with proliferative vitreoretinopathy

.The report on the postoperative changes of AL in RRD-CD patients is rare. Investigating AL changes will contribute to the accurate selection of IOL power and ensure the desired postoperative refraction in RRD-CD patients planning to have combined surgeries.

The present study evaluated the AL changes post PPV in RRD-CD patients compared with RRD patients. The potential factors influencing AL after the PPV surgery were further investigated.

SUBJECTS AND METHODS

This retrospective consecutive cohort study was approved by the Ethics Committee of Beijing Tongren Hospital and adhered to the Declaration of Helsinki. Informed consent was waived due to the retrospective nature of the study.

Medical records of RRD patients who underwent PPV combined with silicone oil tamponade in Beijing Tongren eye center from January 2015 to December 2018 were reviewed.Inclusion criteria: the records of RRD patients who 1)underwent PPV combined with silicone oil tamponade in our hospital; 2) underwent silicone oil removal (SOR) in our hospital after PPV; 3) had AL measurements by the same machine before PPV and before SOR. Based on the type of retinal detachment, the patient records were categorized into RRD-CD and RRD only. CD was defined as detecting peripheral choroidal detachment by either binocular indirect ophthalmoscopy examination or ultrasound scans

.

Exclusion criteria: 1) the records lacking the AL measurement;2) the records without the description of presurgery choroidal status; 3) the AL measurement severely impacted by dense vitreous hemorrhage or dense fibro-membrane that involved the fovea; 4) macula-on RRD.

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The 23-gauge PPV was performed by two surgeons separately.All patients had silicone oil tamponade. Drainage of suprachoroidal fluid or cryotherapy was performed in some RRD-CD patients.

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Underestimated IOL power using the pre-operative AL measurement would be expected to be above 3D according to the previous work on the relationship of AL to the IOL power calculation

. Our findings indicated that using underestimated pre-operative AL measurements to calculate IOL power in RRD-CD patients might result in intolerable refractive errors after combined phacovitrectomy.

RESULTS

To exclude the effect of different operators and machines on AL-repeated measurements, we had one operator use one set of PCI and US to measure each patient’s AL. We also examined the contralateral AL before PPV and before SOR to ensure that the repeated AL measurement was reliable. The consistency of AL in the contralateral eye showed the high reproducibility of the biometric data. To minimize the effect of subretinal fluid movement on the AL measurement when patients were examined from a supine position in the A-scan to a sitting position in the PCI, identifying the signal of the eyeball and configuration of retinal detachment was confirmed by a simultaneously performed B-scan. The results of the A-scan and the PCI were compared

. It has been reported that the macula-off status may influence the measurement of AL

.Therefore, we ruled out macular-on cases to lessen the impact of macular-on status on AL measurement. Therefore, our study only included cases with macula-off RRD in both groups.

此規則下的密碼可以不是一條連續的折線，可以是多條線段或折線。本文設計的限制規則如下：折線或線段至少經過兩個點，所有線經過的點均不能重復，且必須經過所有背景圖形的點。圖6中左圖由于一個點未被經過，故為不合法情況。圖6中中圖由于一個點被經過了兩次，故為不合法情況。……