To summarize, we present a case of exaggerated, non-infective posterior segment inflammation following retinal reattachment surgery that manifested as occlusive haemorrhagic retinal vasculitis on the first post-operative day. The presence of non-infective posterior segment inflammation, most likely caused by the toxicity induced by the retained intraocular cotton fibre, led to the diagnosis of TPSS.

The term TPSS refers to posterior segment inflammation of the eye caused by a reaction or toxicity to any substance used in the surgical procedure. Toxic posterior ocular reactions are usually caused by the use of intracameral adjuvants, such as those used in cataract surgery, or by the use of saline irrigating solution, silicone oil or gas tamponades, or perfluorocarbon liquid during vitreoretinal surgery [3, 4, 6, 7]. Similar hypersensitivity reactions have been noted following the use of intravitreal drugs such as anti-vascular endothelial growth factors or locally compounded antibiotics like vancomycin or even following the use of intraocular dyes such as indocyanine green or Brilliant blue G [8,9,10,11,12]. Substances related to the cleaning of micro cannulated instruments could also be responsible for TPSS. Toxic reactions in TPSS are acute hypersensitivity reactions that occur immediately after surgery and are potentially type 2 cytotoxic or type 3 immune-complex mediated reactions that respond effectively to systemic steroids [13].

Multiple factors, including the re-use of a previously cleaned vitrectomy set or instruments, saline infusion, intraocular air during fluid-air exchange, silicone oil endotamponade, and the presence of intraocular cotton fibre, may have contributed to the development of hypersensitivity in this case. The remaining cases, which were operated on the same day with the same vitrectomy set and instruments, as well as the same batch of silicone oil and saline infusion, showed no toxic intraocular reaction. As a result, we believe the hypersensitivity reaction was caused by an accidentally retained intraocular cotton fibre. In addition, the patient recovered from TPSS with a favourable visual outcome following the disappearance and disintegration of the intraocular cotton fibre and additional treatment with topical and systemic oral corticosteroids. This reinforces our belief that the toxic intraocular reaction was most likely caused by the retained intraocular fibre. However, a contaminated silicone oil vial or saline infusion solution cannot be completely ruled out as the likely source of TPSS in this case.

In conclusion, the appearance of a picture resembling occlusive retinal vasculitis following vitreoretinal surgery indicates exaggerated posterior segment ocular inflammation, which can be potentially vision-threatening in eyes with macular involvement. In such cases, identifying the trigger agent(s), particularly in TPSS clusters, is critical. Topical and systemic steroid treatment is usually effective.