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Intraocular currents, Bernoulli's principle and non-drainage scleral buckling for rhegmatogenous retinal detachment.

ABSTRACT: For many years, it is not fully understood how non-drainage scleral buckling surgery brings about spontaneous reattachment of the detached retina when retinal breaks remain open at the end of surgery. Various explanations have been put forward, but none more interesting than the effect of fluid currents associated with eye movements. One such explanation involved the physics of the Bernoulli's principle. Daniel Bernoulli was an eighteenth century Swiss mathematician and he described an equation based on the conservation of energy. The sum of pressure energy, potential energy and kinetic energy remains constant. Bernoulli's equation usually applies to closed system such as the flow of fluid through pipes. When fluid flows through a constriction, the speed of fluid increases, the kinetic energy increases. If there was no change in elevation (potential energy), then the increase in kinetic energy must be accompanied by a decrease in pressure energy. In ophthalmic surgery, the Bernoulli's effect is the basis for venturi pumps that drive vitrectomy and phacoemulsification machines. This essay expounds on how Bernoulli's effect might be relevant to scleral buckling for retinal detachment repair. In the era when vitrectomy is increasing the primary surgical operation for retinal detachment, the pervasive advice is to emphasise the importance of patient adopting head posture and remaining still postoperatively. The exception is non-drainage scleral buckling surgery. Early postoperative mobilisation may be vital to achieve reattachment.

SUBMITTER: Wong D

PROVIDER: S-EPMC5811744 | biostudies-literature | 2018 Feb

REPOSITORIES: biostudies-literature

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Intraocular currents, Bernoulli's principle and non-drainage scleral buckling for rhegmatogenous retinal detachment.

Wong D D Chan Y K YK Bek T T Wilson I I Stefánsson E E

Eye (London, England) 20180119 2

For many years, it is not fully understood how non-drainage scleral buckling surgery brings about spontaneous reattachment of the detached retina when retinal breaks remain open at the end of surgery. Various explanations have been put forward, but none more interesting than the effect of fluid currents associated with eye movements. One such explanation involved the physics of the Bernoulli's principle. Daniel Bernoulli was an eighteenth century Swiss mathematician and he described an equation ...[more]

PMID: 29350687

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Project description:PurposeTo determine the long-term changes in the intraocular pressure (IOP) following vitrectomy for rhegmatogenous retinal detachment (RRD), epiretinal membrane (ERM), and macular hole (MH), and to investigate the relationship between the retinal disease and the incidence of late-onset IOP elevation.MethodsThis was a retrospective, observational, comparative study. We reviewed the medical records of 54 eyes of 54 RRD patients, 117 eyes of 117 ERM patients, and 75 eyes of 75 MH patients who underwent 20-, 23- or 25-gauge vitrectomy. The IOPs before surgery and 1, 3, 6, and 12 months following vitrectomy, and also at the final visit (average, 23.95 months) were evaluated. We defined a significant increase in the IOP as an increase of ?4 mmHg from the preoperative IOP, and this increase was taken to be a 'death' event for the Kaplan-Meier survival analyses.ResultsThe mean follow-up period was not significantly different among the groups. The mean IOP at 3 (P = 0.001) and 12 (P = 0.011) months following the vitrectomy and at the final visit (P = 0.002) were significantly higher than that before the vitrectomy in the RRD group. The mean IOP in the RRD group was significant higher than that in the ERM group at 1 (P = 0.005), 3 (P = 0.009), and 12 (P = 0.013) months following vitrectomy, and at the final visit (P = 0.032). Kaplan-Meier survival analyses showed that the RRD group had a significantly higher risk of an IOP increase following vitrectomy than the other groups (P<0.001 by log-rank test). Multivariate logistic regression analyses showed that a preoperative diagnosis of RRD was the only risk factor that was significantly associated with a postoperative IOP elevation after excluding eyes with a low preoperative IOP (odds ratio, 3.208; P = 0.003).ConclusionsA late-onset IOP elevation following vitrectomy was observed only in eyes that underwent RRD surgery. The elevation was probably caused by the specific characteristics and surgical procedures of RRD. Clinicians should pay more attention to the IOP elevation for long times after vitrectomy especially in eyes with RRD.

Project description:Purpose:To investigate the characteristics of silicone oil (SO) emulsification after vitrectomy for rhegmatogenous retinal detachment and their possible correlations with clinical factors. Methods:The first 2?mL of washing out fluid after SO removal was collected, and used for the measurement of the size and number of SO droplets using a Multisizer® 3 Coulter counter (Beckman Coulter, USA). The correlations between SO droplets and clinical factors were analyzed. Results:A total of 38 patients (23 males, 15 females) who underwent primary PPV with SO injection for RRD and whose retina stayed attached for ?3 months after SO removal were included in the study. The average number of oil droplets was 1.96?×?106?±?3.95?×?106/mL (range 0.17?×?106 to 21.71?×?106/ml), and 80.8% (range 64.23%-99.07%) of the droplets were 1-2??m in diameter. The total number of emulsified SO droplets was not correlated with any clinical factor (all P > 0.05). When the emulsified SO droplets were divided into groups by their diameter, multiple linear regression revealed that age was negatively correlated with the numbers of 5-7-?m in diameter. The total number of emulsified SO droplets was not correlated with any clinical factor (all ?m in diameter. The total number of emulsified SO droplets was not correlated with any clinical factor (all P > 0.05). When the emulsified SO droplets were divided into groups by their diameter, multiple linear regression revealed that age was negatively correlated with the numbers of 5-7-?m in diameter. The total number of emulsified SO droplets was not correlated with any clinical factor (all ?m in diameter. The total number of emulsified SO droplets was not correlated with any clinical factor (all P > 0.05). When the emulsified SO droplets were divided into groups by their diameter, multiple linear regression revealed that age was negatively correlated with the numbers of 5-7. Conclusion:Using a Multisizer® Coulter counter, we successfully determined the number and size of SO droplets after emulsification. We found that the number of 5-12-?m-diameter droplets was higher in younger-age patients and was higher in patients using antiglaucoma eyedrops.?m in diameter. The total number of emulsified SO droplets was not correlated with any clinical factor (all.

Dataset Information

Intraocular currents, Bernoulli's principle and non-drainage scleral buckling for rhegmatogenous retinal detachment.

Publications

Intraocular currents, Bernoulli's principle and non-drainage scleral buckling for rhegmatogenous retinal detachment.

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