Combination analysis on the impact of the initial vision and surgical time for the prognosis of indirect traumatic optic neuropathy after endoscopic transnasal optic canal decompression

Retinal peripapillary microvasculature in indirect traumatic optic neuropathy predicted prognosis of endoscopic trans-ethmosphenoid optic canal decompression

PURPOSES

The purpose of this study is to quantify the alteration of retinal peripapillary microvasculature and structure in unilateral indirect traumatic optic neuropathy (ITON) and figure out predicted factors of visual improvement for ITON patients with endoscopic trans-ethmosphenoid optic canal decompression (ETOCD) after one month.

METHODS

Twenty healthy controls and 72 unilateral ITON patients were included. Optical coherence tomography angiography was used to analyse radial peripapillary capillary (RPC) density, peripapillary retinal nerve fibre layer (pRNFL) thickness, superficial retinal capillary plexus (SRCP) and deep retinal capillary plexus (DRCP) density. Associations between preoperative parameters and postoperative best-corrected visual acuity (BCVA) were determined. The receiver operating characteristic (ROC) curves were used to figure out predicted factors of visual improvement for ITON after ETOCD one month.

RESULTS

In ITON eyes, the preoperative global RPC density, pRNFL thickness and SRCP density were reduced compared with unaffected eyes (p ≤ 0.001). Multivariate linear regression showed that preoperative global RPC density (Standardized β = -0.273), SRCP density (Standardized β = -0.183), DRCP density (Standardized β = -0.098) and preoperative BCVA (Standardized β = 0.795) were associated with the postoperative BCVA (All p < 0.001). The area under the curve (AUC) of preoperative global RPC density to predict visual improvement after ETOCD was 0.816, while the AUCs of preoperative BCVA, global pRNFL thickness, SRCP and DRCP density were 0.575, 0.756, 0.516 and 0.615, respectively.

CONCLUSIONS

The alteration of peripapillary area, especially the reduced RPC density, occurred in ITON eyes. The preoperative RPC density was associated with postoperative BCVA and was shown to be highly predictive for visual improvement after ETOCD one month.

Vision improvement in indirect traumatic optic neuropathy treated by endoscopic transnasal optic canal decompression

BACKGROUND

Indirect Traumatic optic neuropathy (ITON) is a severe disease characterized by a sudden decline of visual function after craniofacial injury. However, the best treatment for ITON is unknown. Endoscopic transnasal optic canal decompression (ETOCD) has gradually been used for ITON treatment worldwide in recent years.

OBJECTIVE

To assess the effect of ETOCD on visual acuity in patients with ITON and identify factors that affect prognosis.

METHODS

In this study, clinical characteristics of 44 ITON patients who underwent ETOCD in Qilu Hospital of Shandong University were retrospectively analyzed. Factors affecting prognosis were also evaluated.

RESULTS

ETOCD treatment improved the vision of 20 (45.5%) patients with no patient suffering from vision deterioration. The mean value of visual acuity (VA) scores improved from 1.57 to 2.39 (P < 0.001). Patients with residual vision had a better VA improvement percent than those without light perception (66.67% versus 34.48%, χ² = 4.13, P = 0.042). Although shorter duration before ETOCD was associated with better improvement score in ITON patients (r = -0.30, P = 0.044), optic canal fracture (OCF) and optic nerve sheath incision did not affect the prognosis of these patients. Five ITON patients with cerebrospinal fluid rhinorrhea were treated with free nasal mucosal flap during the surgery, and no other severe surgical complication occurred.

CONCLUSIONS

ETOCD can effectively and safely improve the vision of ITON patients, patients with residual vision and those treated earlier may benefit more from this surgery.

Endoscopic trans-ethmosphenoid optic canal decompression is an optimal choice to save vision for indirect traumatic optic neuropathy

Purpose

To evaluate and compare the effectiveness of endoscopic trans‐ethmosphenoid optic canal decompression (ETOCD) and steroid pulse therapy (SPT) for indirect traumatic optic neuropathy (ITON).

Design

Prospective interventional case series.

Methods

Total 140 monocular ITON patients from January 2017 to June 2019 were recruited, including 100 patients received ETOCD (56 patients received ETOCD only and 44 patients received ETOCD combined with SPT before surgery), and 40 patients received SPT only. Their visual acuity (VA) and visual evoked potential (VEP) were analysed before and after treatments. Initial VA, lag time, causes of injuries and age were analysed for evaluating prognosis of treatment.

Results

In contrast with patients received SPT only (15/40 = 38%), the effective rate of patients received ETOCD only and patients received ETOCD combined with SPT were both significantly better (46/56 = 82%, p < 0.001 and 30/44 = 68%, p = 0.005). Whether with SPT before ETOCD or not, after ETOCD, patients with VA improvement showed no significant difference. And 59/76 (77.6%) patients showed improvement within 24 hours. Patients who had residual visions achieved higher effective rate than those with no light perception (56/58 = 97% and 20/42 = 48%; p < 0.001) after ETOCD. For patients with long lag time of 21–90 days, 23/32 (72%) patients presented with vision improvement. Moreover, VEP was significantly improved after ETOCD. No severe complications were observed.

Conclusions

Endoscopic trans‐ethmosphenoid optic canal decompression (ETOCD) is an effective and safe therapy for ITON, which is more effective than SPT. Even for patients with failure in responding to SPT, the successfully physical decompression is the most effective way to rescue optical nerve from permanent damage.

Traumatic optic neuropathy: a review of current studies

Traumatic optic neuropathy (TON) is a serious complication of craniofacial trauma that directly or indirectly damages the optic nerve and can cause severe vision loss. The incidence of TON has been gradually increasing in recent years. Research on the protection and regeneration of the optic nerve after the onset of TON is still at the level of laboratory studies and which is insufficient to support clinical treatment of TON. And, due to without clear guidelines, there is much ambiguity regarding its diagnosis and management. Clinical interventions for TON include observation only, treatment with corticosteroids alone, or optic canal (OC) decompression (with or without steroids). There is controversy in clinical practice concerning which treatment is the best. A review of available studies shows that the visual acuity of patients with TON can be significantly improved after OC decompression surgery (especially endoscopic transnasal/transseptal optic canal decompression (ETOCD)) with or without the use of corticosteroids. And new findings of laboratory studies such as mitochondrial therapy, lipid change studies, and other studies in favor of TON therapy have also been identified. In this review, we discuss the evolving perspective of surgical treatment and experimental study.

Microanatomic Study of the Optic Canal

BACKGROUND

The continuous development of microsurgical techniques to treat lesions in and around the optic canal (OC) emphasizes the need for an accurate understanding of the microanatomy of the region.

METHODS

Forty anatomic specimens were studied, with emphasis on the OC. The sphenoid bone and related structures were decalcified, added to animal gelatin, cut into 1-mm thick slices, and observed through a surgical microscope. The OC was considered the course that contained exclusively the optic nerve (ON) and ophthalmic artery.

RESULTS

The mean distance between the medial walls of the OC was 12.2 mm, and the OC had an average length of 12.06 mm. The OC has a horizontal oval shape in the proximal (internal) segment; a round shape in the middle segment; and a vertical oval shape in the distal (external) segment at the orbital cavity. In the middle segment of the OC, the thickest wall of the OC was the lateral (average: 0.68 mm), while the medial, inferior, and superior wall measures had averages of 0.75, 0.40, and 0.39 mm, respectively. The lateral wall of the sphenoid sinus is located under the OC, and the inferior wall of the OC separates both structures. The ophthalmic artery inside the OC was always located under the ON, between the dural sheaths, and had an average diameter of 1.03 mm.

CONCLUSIONS

The neurovascular structures within the OC vary in size and shape. The anatomic knowledge of the OC and its variations allows better surgical results and minimizes the surgical morbidity.

The retinal vasculature pathophysiological changes in vision recovery after treatment for indirect traumatic optic neuropathy patients

Purpose

To evaluate the retinal vasculature pathophysiological changes of indirect traumatic optic neuropathy (ITON) patients after effective surgery.

Methods

Monocular ITON patients who underwent endoscopic trans-ethmosphenoid optic canal decompression (ETOCD) or conservative treatments in Zhongshan Ophthalmic Center from January 2017 to June 2020 were recruited. Visual acuity (VA), visual evoked potential (VEP), oxygen saturation of retinal blood vessels (SO₂), and optical coherence tomography angiography (OCT-A) were measured. All patients were followed up at least 3 months after treatments.

Results

A total of 95 ITON patients were recruited, including 77 patients who underwent ETOCD and 18 patients who underwent conservative treatments. After treatments, more patients received ETOCD (59/77 = 76.6%) presented with improved VA compared with the patients with conservative treatments (6/18 = 33.3%). Compared with the pre-therapeutic measurements, VEP were significantly improved after surgery in ETOCD-treated patients (P < 0.05). Latent periods of P1 and N2, as well as amplitude of P2 of VEP parameters, showed more sensitive to vision recovery (P < 0.05). Retinal artery SO₂ and the differences between arteries and veins were improved in ETOCD-treated patients (P < 0.05). Meanwhile, with OCT-A examination, the retinal thickness and retinal vessel density were notably better in ETOCD-treated patients after surgery than that in patients received conservative treatments (P < 0.05).

Conclusions

Vision recovery after effective treatment of ITON patients was associated with the increased oxygen saturation of retinal vessels, better availability of oxygen in the retina, greater vessel density, and thicker retinas, which might further underlie the vasculature mechanism of vision recovery in ITON patients.

Traumatic Optic Neuropathy

A host of different types of direct and indirect, primary and secondary injuries can affect different portions of the optic nerve(s). Thus, in the setting of penetrating as well as nonpenetrating head or facial trauma, a high index of suspicion should be maintained for the possibility of the presence of traumatic optic neuropathy (TON). TON is a clinical diagnosis, with imaging frequently adding clarification to the full nature/extent of the lesion(s) in question. Each pattern of injury carries its own unique prognosis and theoretical best treatment; however, the optimum management of patients with TON remains unclear. Indeed, further research is desperately needed to better understand TON. Observation, steroids, surgical measures, or a combination of these are current cornerstones of management, but statistically significant evidence supporting any particular approach for TON is absent in the literature. Nevertheless, it is likely that novel management strategies will emerge as more is understood about the converging pathways of various secondary and tertiary mechanisms of cell injury and death at play in TON. In the meantime, given our current deficiencies in knowledge regarding how to best manage TON, "primum non nocere" (first do no harm) is of utmost importance.

Interventions for Indirect Traumatic Optic Neuropathy: A Report by the American Academy of Ophthalmology

PURPOSE

To review the literature on the efficacy and safety of medical and surgical interventions for indirect traumatic optic neuropathy (TON), defined as injury to the nerve that occurs distal to the optic nerve head.

METHODS

A literature search was conducted on October 22, 2019, and updated on April 8, 2020, in the PubMed database for English language original research that assessed the effect of various interventions for indirect TON. One hundred seventy-two articles were identified; 41 met the inclusion criteria outlined for assessment and were selected for full-text review and abstraction. On full-text review, a total of 32 studies met all of the study criteria and were included in the analysis.

RESULTS

No study met criteria for level I evidence. Seven studies (1 level II study and 6 level III studies) explored corticosteroid therapy that did not have uniformly better outcomes than observation. Twenty studies (3 level II studies and 17 level III studies) assessed optic canal decompression and the use of corticosteroids. Although visual improvement was noted after decompression, studies that directly compared surgery with medical therapy did not report uniformly improved outcomes after decompression. Four studies (1 level II study and 3 level III studies) evaluated the use of erythropoietin. Although initial studies demonstrated benefit, a direct comparison of its use with observation and corticosteroids failed to confirm the usefulness of this medication. One study (level II) documented visual improvement with levodopa plus carbidopa. Complication rates were variable with all of these interventions. Pharmacologic interventions generally were associated with few complications, whereas optical canal decompression carried risks of serious side effects, including hemorrhages and cerebrospinal fluid leakage.

CONCLUSIONS

Despite reports of visual improvement with corticosteroids, optic canal decompression, and medical therapy for indirect TON, the weight of published evidence does not demonstrate a consistent benefit for any of these interventions. In summary, no consensus exists from studies published to date on a preferred treatment for TON. Treatment strategies should be customized for each individual patient. More definitive treatment trials will be needed to identify optimal treatment strategies for indirect TON.