Page 84 - GTM-3-2

Global Translational Medicine Neuropathic pain after 23-gauge sclerotomy

1. Introduction adhered to the principles outlined in the Declaration of
Helsinki and were approved by the Tehran University of
According to the International Association for the Study Medical Science’s Institutional Review Board (Ethic Code:
of Pain, pain is defined as an unpleasant sensory and IR.TUMS.IKHC.REC.1397.162). Informed consent was
emotional experience associated with or bears resemblance obtained from each participant before inclusion in the
to actual or potential tissue damage. Nociceptors play study.
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the main role in neural encoding of noxious stimuli
such as trauma, surgery, or inflammation which damage Following thorough ophthalmic examination, including
nerve terminals. Acute nociceptive pain is a subjective slit-lamp (Haag-Streit, Mason, OH, USA), dilated fundus
perception with a direct link to consciousness, arising from examination, and intraocular pressure measurement using
a complex process in the central nervous system. Under the Goldmann applanation tonometer (AT-900; Haag-
some pathologic circumstances, a pain that continues to be Streit AG, Koniz, Switzerland) mounted on the slit-lamp
perceived beyond the healing process or even exacerbates microscope, patients were scheduled for the appropriate
after surgery/tissue injury is called neuropathic pain. 2 surgery. Patients with difficulty in communication, a
history of psychiatric, cerebrovascular, or neurologic
Persistent post-operative perception of ocular disease, alcohol consumption, or using illicit drugs,
discomfort in the absence of painful stimuli is called ocular analgesics, or opioids within the past 48 h of the surgery
neuropathic pain. In such situations, patients experience were excluded from the study.
pain, foreign body sensation, tearing, or photophobia
in response to benign stimuli such as blinking. This is In the operating room, patients were prepared for
called allodynia, which is one of the features of ocular the surgery with local or general anesthesia. For local
neuropathic pain. Patients’ symptoms outweigh objective anesthesia, a combination of 0.02 mg/kg midazolam
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signs of ocular surface defects such as cornea staining and 1 mcg/kg fentanyl was administered for intravenous
4-7
and/or conjunctival injection. Altered nerve ending sedation; following blood pressure monitoring, peribulbar
signaling following collateral injury to the branches of the injection of lidocaine 2% and marcaine was performed.
trigeminal nerve during surgery is postulated as the main For general anesthesia, midazolam 0.02 mg/kg, fentanyl
predisposing factor. With surgical trauma, even the density 2 mcg/kg, atracurium 0.5 mg/kg, and propofol 2 mg/
of goblet cells in the conjunctiva may change. kg were employed. Two to three scleral incisions
were conducted 3 to 4 mm posterior to the limbus on
Neuropathic ocular pain has overlapping symptoms inferotemporal, superonasal, and superotemporal sites. In
with dry eye syndrome and has sensory, psychic, occasional cases when a watertight seal of the sclerotomy
cognitive, and behavioral elements. Patients with genetic site was not achieved at the conclusion of surgery, Vicryl
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predisposing factors as well as those with fibromyalgia or 8-0 or 7-0 absorbable sutures were placed. All surgeries
psychiatric diseases such as depression are more susceptible were performed by two experienced vitreoretinal surgeons
to developing persistent post-operative pain. Similar to (N.E. or M.I.). All patients also underwent slit-lamp
8,9
dry eye syndrome, it is more common in females and older examination and intraocular pressure measurement on
populations. 5,10 day 1, week 1, month 1, and month 2 after the surgery.
Well-known ocular surgeries associated with ocular We assessed persistent pain in patients using the Persian
neuropathic pain include laser refractive surgery and version of the standardized brief pain inventory (BPI)
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cataract surgery. However, few studies evaluated retinal questionnaire, immediately before surgery and 2 months
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surgeries in this regard. In this study, we aimed to evaluate after surgery. BPI is a multidimensional measurement tool,
the frequency of symptoms of ocular neuropathic pain after which has been validated in the Iranian population. A
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vitreoretinal surgeries involving a 23-gauge sclerotomy. body figure is presented to the patient, on which the site
We have also investigated the effect of different variables of pain can be marked. The questionnaire has an 11-point
such as demographic factors and underlying conditions on numeric scale; the “0” corresponds to no symptoms, and
post-operative symptoms. the “10” indicates the worst imaginable symptom. The

2. Materials and methods following items were evaluated: Deep eye pain, irritation,
photophobia, tearing, foreign body sensation, deep head
This observational study was conducted on patients who and facial pain, and numbness. The average of all items,
underwent 23-gauge (23G) sclerotomy incisions including defined as the overall eye pain score, was calculated to
pars plana vitrectomy and silicone removal. The study was evaluate the correlation of ocular manifestations with
conducted in a tertiary educational hospital from June demographic characteristics and systemic conditions. BPI
2021 to January 2022. The study protocol and procedures questionnaire also evaluates the interference of symptoms

Volume 3 Issue 2 (2024) 2 doi: 10.36922/gtm.1770