Purpose
To evaluate choroidal thickness (CT) and its variation during the water drinking test (WDT) in emmetropic (EE) and myopic (ME) eyes using Spectral-Domain Optical Coherence Tomography (SD-OCT).
Methods
Prospective evaluation of 80 eyes (40 myopic and 40 emmetropic eyes from 20 healthy patients in each group) submitted to the water drinking test and SD-OCT macular scans performed 10 minutes and 45 minutes after water ingestion. WDT was performed under standard conditions and consisted of intraocular pressure (IOP) measurement followed by ingestion of 1000 ml of tap water in five minutes and Goldmann applanation tonometry at 15, 30 and 45 minutes after starting the WDT. For statistical analysis, foveal CT as well as CT at 3 mm nasally and 3 mm temporally to the fovea were obtained.
Results
Mean spherical equivalent refraction was 0.10±0.33 in emmetropic and -6.89±1.59 diopters in myopic eyes (p<0.001). IOP measurements during the WDT are shown in tables 1 and 2. Peak IOP was 14.6±2.7 mmHg and 14.0±2.0 mmHg (EE and ME, respectively). No statistical differences were found during WDT response between EE and ME. EE presented higher CT in both foveal and 3 mm nasal to the fovea, compared to myopic eyes, as shown in table 3 (336.65±70.08 vs 247.85±88.55; p<0.0001; and 150.77±62.31 vs 113.90±51.90; p=0.006, respectively). Statistically significant diferences were demonstrated at foveal CT, 10 minutes after water ingestion in both EE and ME. EE group: 2,67% thickness rise; p<0.0001. ME group: 3,45% thickness rise; p<0.0001. There was no correlation between peak IOP during WDT and CT thickness in EE (Pearson’s correlation coefficient = -0.06; p=071). A weak correlation between peak IOP during WDT and CT thickness was demonstrated in ME (Pearson’s correlation coefficient = 0.36; p=0.01).
Conclusions
In our sample,CT was thinner in myopic eyes than in emmetropic eyes. Statistically significant IOP rise was detected during WDT in both emmetropic and myopic eyes.Statistically significant foveal CT rise was detected 10 minutes after water ingestion in both emmetropic and myopic eyes. A weak correlation between peak IOP during the WDT was found in myopic eye; although the same did not occur in emmetropic eyes.
Keywords: 452 choroid •
568 intraocular pressure •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)