Reece Landers

Even though vitrectomies have been performed routinely for over 40 years, the effect that temperature has on the vitreous and retinal surfaces during the procedure have not been measured before, noted Dr Reece Landers (University of North Carolina, Chapel Hill, North Carolina, USA) when discussing his reasons for performing a recent study on this topic.¹

"Therapeutic hypothermia is being used more and more throughout medicine these days, with many benefits, but also with some possible bad side effects," he continued. "We determined that that we are in fact inducing hypothermia to the retina and vitreous during vitrectomy with unknown (but probably minimal) side effects."

Effect of temperature

It is commonly known that therapeutic hypothermia will help to prevent ischaemic damage caused to tissues through a reduction in the blood flow as a result of surgery and trauma. However, in vitrectomy the extent to which the retina is cooled is not known.

"Fortunately," Dr Landers added, "using room temperature infusion fluid during a victrectomy, which induces hypothermia in the retina and vitreous (and probably other structures inside the eye, such as the lens) seems to have minimal side effects."

One of the main concerns and side effects of vitrectomy is cataract. "Many patients undergoing a vitrectomy develop a cataract in their lens sooner than in their nonvitrectomized eye. We don't know the reason for this. It is just possible that it is somehow related to the induced hypothermia... but this is still speculative," he explained.

The study

To examine the temperature changes within the vitreous fluid and retinal surface, Dr Landers and colleagues measured the intraocular temperature with a 23gauge (23G) thermoprobe before, during and after vitrectomy. "Prior to doing this research, we did not know how much the temperature of the retina would drop during the study," Dr Landers said. "We did not know to what degree the underlying choroidal circulation would keep the inner retina near its normal temperature during vitrectomy desipte the eye being filled with relatively cool room temperature infusion fluid. It turned out that the temperature of the retina dropped quite a bit during surgery." The changes in temperature that were recorded during the study were found to be statistically significant in difference.

This prospective study, however, included only six patients and Dr Landers emphasized a need for further research to fully examine what possible effects this change in temperature could have. "Ideally, a larger and longerterm study shoud be performed, possibly even a controlled study that compares the effects of room temperature infusion fluid and warmer, possibly body temperature, infusion fluid to see if the warmed fluid produces fewer cataracts," Dr Landers said. "We are continuing our measurements to obtain larger data sets and we are also testing differing conditions, such as retinal detachments and other situations."

Special contributor

Dr Reece Landers, MD, is a vitreoretinal surgeon at the University of North Carolina, Chapel Hill, North Carolina, USA. He may be reached by Email: maurice_landers@med.unc.edu

Dr Landers has no financial interests in the subject matter.

Reference

1. M.B. Landers 3rd et al., Retina, 2012; 32(1):172–176.