Influence of Tumor Characteristics on Visual Field Outcomes After Pituitary Adenoma Surgery

Background: There were few reports about the influence of tumor characteristics on the postoperative visual field outcomes after transsphenoidal surgery for pituitary adenoma. The purpose of this study was to explore the tumor characteristics that influenced perioperative visual field changes. Methods: Patients who underwent transsphenoidal surgery under a diagnosis of pituitary adenoma at the Kyoto University Hospital between April 2012 and December 2018 were retrospectively enrolled. Correlations among circumpapillary retinal nerve fiber layer thickness, preoperative and postoperative mean deviation (MD) of visual field, MD change after the surgery, and maximum tumor diameter were evaluated by measuring Pearson correlation coefficient. We evaluated the influences on postoperative MD using a generalized estimating equation for univariate and multivariate regression analyses. We also compared the characteristics of cystic and solid tumors. Results: Thirty-two eyes of 18 patients were included in this study (9 male and 9 female patients). Postoperative MD positively correlated with maximum tumor diameter only in multivariate regression {β = 0.22 (95% confidence interval [CI], 0.004-0.43), P = 0.046}, although maximum tumor diameter negatively correlated with postoperative MD in univariate regression (β = -0.16 [95% CI, -0.58 to 0.26], P = 0.46). In the investigation of perioperative MD changes, eyes with cystic tumors showed significantly better improvement those with solid tumors (8.93 ± 7.85 vs 0.18 ± 6.56 dB, P = 0.007). Conclusions: Cystic and solid tumors show different characteristics of visual loss and visual field defects. The MD in eyes with cystic tumors improved significantly more than that in eyes with solid tumors.

Original Contribution Section Editors: Clare Fraser, MD Susan Mollan, MD Influence of Tumor Characteristics on Visual Field Outcomes After Pituitary Adenoma Surgery Munekatsu Ito, MD, Kenji Suda, MD, PhD, Eri Nakano, MD, PhD, Miho Tagawa, MD, PhD, Manabu Miyata, MD, PhD, Satoshi Kashii, MD, PhD, Masahiro Tanji, MD, PhD, Susumu Miyamoto, MD, PhD, Akitaka Tsujikawa, MD, PhD Background: There were few reports about the influence of tumor characteristics on the postoperative visual field outcomes after transsphenoidal surgery for pituitary adenoma. The purpose of this study was to explore the tumor characteristics that influenced perioperative visual field changes. Methods: Patients who underwent transsphenoidal surgery under a diagnosis of pituitary adenoma at the Kyoto University Hospital between April 2012 and December 2018 were retrospectively enrolled. Correlations among circumpapillary retinal nerve fiber layer thickness, preoperative and postoperative mean deviation (MD) of visual field, MD change after the surgery, and maximum tumor diameter were evaluated by measuring Pearson correlation coefficient. We evaluated the influences on postoperative MD using a generalized estimating equation for univariate and multivariate regression analyses. We also compared the characteristics of cystic and solid tumors. Results: Thirty-two eyes of 18 patients were included in this study (9 male and 9 female patients). Postoperative MD positively correlated with maximum tumor diameter only in Department of Ophthalmology and Visual Sciences (MI, KS, EN, Miho Tagawa, MM, AT), and Department of Neurosurgery (Masahiro Tanji, SM), Kyoto University Graduate School of Medicine, Kyoto, Japan; Department of Ophthalmology (MI), Kurashiki Central Hospital, Okayama, Japan; and Department of Vision Science (SK), Aichi Shukutoku University School of Health and Medical Science, Aichi, Japan. This research was supported in part by a research grant from Alcon Japan ltd. The funding organization had no role in the design or conduct of this research. The authors report no conflicts of interest. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www. jneuro-ophthalmology.com). Ethics approval: This retrospective study adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board and Ethics Committee of the Kyoto University Graduate School of Medicine. Address correspondence to Kenji Suda, MD, PhD, Department of Ophthalmology and Visual Sciences, Kyoto University Graduate School of Medicine, 54 Shougoin Kawahara-cho, Sakyo-ku, Kyoto 606-8507, Japan; E-mail: [e-mail] 376 multivariate regression {b = 0.22 (95% confidence interval [CI], 0.004–0.43), P = 0.046}, although maximum tumor diameter negatively correlated with postoperative MD in univariate regression (b = 20.16 [95% CI, 20.58 to 0.26], P = 0.46). In the investigation of perioperative MD changes, eyes with cystic tumors showed significantly better improvement those with solid tumors (8.93 ± 7.85 vs 0.18 ± 6.56 dB, P = 0.007). Conclusions: Cystic and solid tumors show different characteristics of visual loss and visual field defects. The MD in eyes with cystic tumors improved significantly more than that in eyes with solid tumors. Journal of Neuro-Ophthalmology 2023;43:376–382 doi: 10.1097/WNO.0000000000001735 © 2022 by North American Neuro-Ophthalmology Society P ituitary tumors constitute 12%–15% of all intracranial lesions (1). Visual impairment is the most common complaint, with vision loss occurring in 32%–70% of patients (1). The visual field of patients with pituitary adenoma usually recovers after transsphenoidal surgery for the removal of the tumor (2). The prognostic value of factors, such as age, duration of symptoms, tumor size, and volume, preoperative visual acuity or visual field loss, optic atrophy, and pattern electroretinograms, have been explored with respect to vision loss, but none of these factors was shown to consistently predict visual recovery after the surgery (3,4). Optical coherence tomography (OCT) can identify reduction of the retinal nerve fiber layer thickness (RNFLT) (3–7). Pituitary adenomas can compress the optic chiasm, causing RNFLT reduction (3–5,8,9). The functional impairment of the visual field caused by pituitary adenomas can also be evaluated quantitatively by the measurement of mean deviation (MD) in static perimetry, which represents the average difference from the normal expected value in the specific age-group patients (10). Previous studies have suggested that the preoperative circumpapillary RNFLT (cpRNFLT) significantly correlated with the difference Ito et al: J Neuro-Ophthalmol 2023; 43: 376-382 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution between preoperative and postoperative MD (3,7), but there were few reports about the influence of tumor characteristics and cpRNFLT on the postoperative visual field outcomes after transsphenoidal surgery for pituitary adenoma. First, we explored the correlations between postoperative MD and maximum tumor diameter using a generalized estimating equation (GEE) for univariate and multivariate regression analyses. We found that tumor diameter was not less correlated than cpRNFLT with postoperative MD. Second, we focused on the tumor characteristics and compared the characteristics of cystic and solid tumors. METHODS This retrospective study adhered to the tenets of the Declaration of Helsinki and was approved by the Institutional Review Board and Ethics Committee of the Kyoto University Graduate School of Medicine. Inclusion Criteria Patients who underwent treatment at the Kyoto University Hospital between April 2012 and December 2018 were retrospectively enrolled. The inclusion criteria were as follows: (1) patients who were referred from the department of neurosurgery for assessments of visual acuity and visual field, (2) patients who underwent transsphenoidal surgery and were pathologically diagnosed as showing pituitary adenoma, and (3) eyes that underwent Spectralis HRA +OCT (Heidelberg Engineering, Heidelberg, Germany) examinations before the surgery and automated visual field analyzer (HFA; Carl Zeiss-Meditec, Dublin, CA) assessments using the 30-2 SITA standard testing protocol both before and after the surgery. Exclusion Criteria We excluded patients who showed no bitemporal hemianopsia defined by Mills criteria (see below) in automated visual field analyzer assessments both before and after the surgery (10). field sensitivity at each test point was evaluated with reference to the total deviation from a normative database or the pattern deviation from comparison with the findings for other test points in the same examination. In this study, we defined temporal hemianopia in HFA results based on Mills criteria (10), that is, a threshold sensitivity difference of 2 dB or more for 4 pairs along the vertical median or 3 dB or more for 3 pairs along the vertical median was diagnosed as a temporal hemianopia (10). MRI We measured the length of the tumor in the axial, coronal, and sagittal planes. The maximum length was chosen as the maximum tumor diameter in these measurements. The type of tumor (cystic or solid tumor) was retrospectively determined by the reports from radiologists or conference records at the neurosurgery department. Statistical Analyses Comparisons of categorical data were performed by Fisher exact test. Correlations among cpRNFLT, preoperative and postoperative MD, MD change after the surgery, and maximum tumor diameter were evaluated by measuring Pearson correlation coefficient. To compare the means between 2 groups and evaluate the influences on postoperative MD, we used a GEE for univariate and multivariate regression analyses. In the GEE framework, each eye was considered dependent within an individual. In the multiple regression analysis, we included age, sex, cpRNFLT, MD in HFA, maximum diameter of the tumor, and visual acuity as the predictive preoperative factors. All P values were presented as two-sided values. Statistical significance was defined as P , 0.05. All analyses were performed using R ver. 3.6.0. (R Foundation for Statistical Computing, Vienna, Austria). RESULTS Patients Optical Coherence Tomography Quantitative RNFL measurements were obtained using the Spectralis OCT instrument with the built-in software. The average RNFL thickness for the entire circumference around the optic disc—at a diameter of 3.46 mm—was obtained for each eye with a mean of 16 scans. Visual Field Testing Automated perimetry was conducted using HFA SITA standard 30-2. Only VF tests with reliable results were used for analysis; reliability was defined in terms of fixation loss ,20% and false-positive error rate and false-negative rate of ,33%. In automated perimetry, the reduction in visual Ito et al: J Neuro-Ophthalmol 2023; 43: 376-382 Among the 1844 patients referred from the department of neurosurgery to the department of ophthalmology, 159 were diagnosed with pituitary adenoma and underwent transsphenoidal surgery between January 2012 and December 2018. A total of 23 patients underwent automated visual field tests before and after the surgery and OCT before the surgery. Five eyes of 5 patients were excluded because they were not diagnosed with bitemporal hemianopia based on Mills criteria. Thus, 32 eyes of 18 patients were eventually included for the subsequent analyses. Baseline characteristics of the patients and the results of preoperative and postoperative examinations are summarized in Table 1. 377 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 1. Characteristics of patients Total Patients/eyes Age, years Sex (male/female) Eye (right/left) Preoperative visual acuity (logMAR) Postoperative visual acuity (logMAR) Preoperative mean deviation, dB Postoperative mean deviation, dB Period until postoperative HFA assessment, days Change in mean deviation, dB cpRNFLT, mm Maximum diameter of the tumor, mm 18/32 58.04 ± 11.81 16/16 16/16 0.15 ± 0.42 20.06 ± 0.20 211.34 ± 10.02 26.51 ± 7.78 428.81 ± 544.43 4.83 ± 8.42 81.75 ± 15.45 27.26 ± 6.94 cpRNFLT, circumpapillary retinal nerve fiber layer thickness; HFA, automated field analyzer; logMAR, logarithm of the Minimum Angle of Resolution. Correlations Between Circumpapillary Retinal Nerve Fiber Layer Thickness and Visual Field Outcome The correlations between cpRNFLT and visual field outcomes are depicted in Supplemental Digital Content (see Figure 1, http://links.lww.com/WNO/A638). The cpRNFLT correlated significantly with both preoperative and postoperative MD, although it showed a stronger correlation with the postoperative MD (P , 0.001, see Supplemental Digital Content, Figure 1A, http://links.lww. com/WNO/A638) than with the preoperative MD (P = 0.004, see Supplemental Digital Content, Figure 1B, http://links.lww.com/WNO/A638). Preoperative cpRNFLT did not correlate significantly with the magnitude of MD change from the preoperative to the postoperative assessment (P = 0.36, see Supplemental Digital Content, Figure 1C, http://links.lww.com/WNO/A638). using a GEE (Table 2). Postoperative MD significantly correlated with cpRNFLT {b = 0.34 (95% confidence interval [CI], 0.14–0.53), P , 0.001 in univariable regression; b = 0.20 [95% CI, 0.07–0.33], P = 0.0025 in multivariate regression}. Postoperative MD correlated with preoperative MD or preoperative visual acuity (logMAR) only in univariable regression (b = 0.5 [95% CI, 0.14–0.86], P = 0.0065 or b = 210.5 [95% CI, 219.5 to 21.51], P = 0.022). Postoperative MD positively correlated with maximum tumor diameter only in multivariate regression (b = 0.22 [95% CI, 0.004–0.43], P = 0.046), although maximum tumor diameter negatively correlated with postoperative MD in univariate regression (b = 20.16 [95% CI, 20.58 to 0.26], P = 0.46, Table 2. The maximum tumor diameter also showed a negative correlation with cpRNFLT but not significantly (r = 20.17, P =0.44). Size and Tumor Characteristics The Factors Influencing Postoperative Mean Deviation To evaluate the factors influencing postoperative MD, we performed univariate and multivariate regression analysis To explore why the correlations between postoperative MD and maximum tumor diameter differed between univariate and multivariate regressions, we sequentially evaluated the type of tumor. As shown in Figure 1, 2 eyes had maximum TABLE 2. Univariate and multivariate regression analysis using the general estimating equation to evaluate the factors influencing postoperative mean deviation Univariate Regression cpRNFLT Preoperative MD Age at surgery Sex (male = 0, female = 1) Maximum tumor diameter Preoperative visual acuity (logMAR) Multivariate Regression b (95% CI) P b (95% CI) P 0.34 (0.14 to 0.53) 0.50 (0.14 to 0.86) 0.25 (20.044 to 0.55) 20.41 (26.5 to 5.6) 20.16 (20.58 to 0.26) 210.5 (219.5 to 21.51) ,0.001 0.0065 0.095 0.89 0.46 0.022 0.20 (0.070–0.33) 0.28 (20.038 to 20.61) 0.13 (20.028 to 0.28) 20.75 (24.6 to 3.1) 0.22 (0.004–0.43) 21.1 (26.3 to 4.08) 0.0025 0.083 0.11 0.7 0.046 0.68 CI, confidence interval; cpRNFLT, circumpapillary retinal nerve fiber layer thickness; logMAR, logarithm of the Minimum Angle of Resolution; MD, mean deviation. 378 Ito et al: J Neuro-Ophthalmol 2023; 43: 376-382 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution TABLE 3. Characteristics of patients in the cystic tumor and solid tumor groups Total Cystic Solid P Age, years Sex 58.04 ± 11.81 59.03 ± 12.54 56.92 ± 11.27 0.41 Male Female 16 16 11 6 5 10 0.16 Eye Right 17 8 Left 14 9 Preoperative visual acuity (logMAR) 0.15 ± 0.42 0.33 ± 0.50 Postoperative visual acuity (logMAR) 20.06 ± 0.20 20.02 ± 0.26 Preoperative mean deviation, dB 211.34 ± 10.02 216.87 ± 9.51 Postoperative mean deviation, dB 26.51 ± 7.78 27.94 ± 9.58 Period until postoperative HFA assessment, days 428.81 ± 544.43 470.06 ± 659.19 Change in mean deviation, dB 4.83 ± 8.42 8.93 ± 7.85 Preoperative cpRNFLT, mm 81.75 ± 15.45 78.00 ± 18.34 Maximum tumor diameter, mm 27.68 ± 6.94 31.13 ± 6.78 8 7 20.05 ± 0.16 20.12 ± 0.07 25.08 ± 6.32 24.90 ± 4.88 382.07 ± 394.10 0.18 ± 6.56 86.00 ± 10.37 22.79 ± 3.78 1 0.004 0.17 ,0.001 0.29 0.77 0.002 0.23 0.003 cpRNFLT, circumpapillary retinal nerve fiber layer thickness; HFA, automated field analyzer; logMAR, logarithm of the Minimum Angle of Resolution. tumor diameters greater than 40 mm. We excluded these 2 eyes as outliers and performed univariate and multivariate analyses (see Supplemental Digital Content, Table 1, http://links.lww.com/WNO/A638). When these eyes were excluded as outliers, the maximum tumor diameter was no longer correlated with postoperative MD in univariable regression (b = 20.40 [95% CI, 20.98 to 0.18], r = 20.37, P = 0.18) (Fig. 1) and in multivariable regression (b = 0.15 [95% CI, 20.18 to 0.48], P = 0.38, Figure 1 and Supplemental Digital Content (see Table 1, http://links. lww.com/WNO/A638). Also, the maximum tumor diame- ter was no longer correlated with change in the MD (b = 0.47 [95% CI, 20.09 to 21.1], r = 0.40, P =0.10, in univariable regression). However, the maximum tumor diameter still showed a significant negative correlation with cpRNFLT (b = 21.43 [95% CI, 22.8 to 0.047], r = 20.48, P =0.04, in univariable regression). Because the tumors with maximum diameter greater than 40 mm had a cystic component, we compared the characteristics between eyes with cystic and solid tumors (Table 3). Preoperative visual acuity (logMAR) and preoperative MD in the eyes with solid tumors were significantly FIG. 1. Relationships of maximum tumor diameter with postoperative MD and circumpapillary retinal fiber layer. A. Maximum tumor diameter did not correlate significantly with postoperative MD (r = 20.18, P = 0.46, solid line). When we excluded 2 eyes with maximum tumor diameter greater than 40 mm, the maximum tumor diameter negatively correlated with postoperative MD but not significantly (r = 20.37, P = 0.18, dotted line). B. Maximum tumor diameter did not correlate significantly with circumpapillary retinal nerve fiber layer thickness (r = 20.17, P = 0.44, solid line). When we excluded 2 eyes with maximum tumor diameter more than 40 mm, the maximum tumor diameter negatively correlated significantly with circumpapillary retinal nerve fiber layer thickness (r = 20.48, P = 0.04, dotted line). C. Maximum tumor diameter correlated significantly with change in MD (r = 0.61, P = 0.0089, solid line). When we excluded 2 eyes with maximum tumor diameter more than 40 mm, the maximum tumor diameter also negatively correlated with change in MD but not significantly (r = 0.40, P = 0.10, dotted line). Each dot in the scatter plots represents 1 eye. White circle indicates cystic tumors and black indicates solid tumors. MD, mean deviation Ito et al: J Neuro-Ophthalmol 2023; 43: 376-382 379 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution better than those in eyes with cystic tumors (P = 0.02 and P , 0.001 respectively). The MD in eyes with cystic tumors improved significantly more than that in eyes with solid tumors (P = 0.002), but there was no significant difference in postoperative MD between eyes with cystic and solid tumors. Maximum tumor diameter in eyes with cystic tumors was significantly larger than that in eyes with solid tumors. The representative cases with cystic tumor or solid tumor are depicted in Figure 2. DISCUSSION The MD of HFA in patients with cystic tumors significantly improved more than that in patients with solid tumors. The maximum diameter of cystic tumors was significantly larger than that of solid tumors (Table 3). The preoperative MD of cystic tumors was significantly lower than that of solid tumor, and the change in MD of cystic tumors was larger than that of solid tumors (Table 3). These findings suggest that the visual field defect caused by cystic tumors has reversible elements. The rapid growth of cystic tumors is believed to cause a rapid reduction in visual acuity. As a result, treatment is started relatively early, and tumor compression is released before irreversible degeneration of the optic nerve. Only a few reports on the surgical outcomes of cystic pituitary adenoma have described the visual prognosis. However, many reports have described the results of preservation of facial nerve function in cystic and solid vestibular schwannomas (VSs) (11,12). In patients with VSs, a relatively rapid increase in volume followed by the appearance of acute symptoms as a result of compression of FIG. 2. Automated field analyzer (HFA) and optical coherence tomography (OCT) in a case showing improvement in cystic tumor. Preoperative HFA findings (A). Postoperative HFA findings (B). Preoperative OCT findings (C). HFA and OCT findings in a case showing a little improvement in solid tumor. Preoperative HFA findings (D). Postoperative HFA findings (E). Preoperative OCT findings (F). Coronal MRI findings of the brain. Cystic tumor (G). Solid tumor (H). HFA, automated field analyzer; OCT, optical coherence tomography. 380 Ito et al: J Neuro-Ophthalmol 2023; 43: 376-382 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution facial nerve are frequently observed in cases involving cystic tumors. Moreover, in relation to symptoms, cystic VSs differ from solid tumors in the patterns of onset. This difference may result from differences in the progression rate because cystic tumors increase more rapidly than solid tumors (11,13,14). The enlargement of cystic tumors is augmented by fluid accumulation due to a direct osmotic effect and/or extravasation of serum proteins from an impaired blood–tumor barrier (13). Most studies on cystic VSs reported that facial nerve outcomes after cystic VS resection were worse than the results for solid VSs of comparable sizes (14). This difference may be due to the tight adhesion of the nerve to the tumor surface, causing difficulties in preserving the arachnoidal plane, unusual positioning of displacement dependent on the pattern of development and growth of the cyst, and the low resistance to traction after cyst evacuation. In some studies, facial nerve outcomes showed no significant difference between cystic and solid VSs (11,15). However, all studies showed a consensus that cystic tumors enlarge more rapidly than solid tumors. Thus, the visual field improvement in patients with cystic tumors is expected to be better than that in patients with solid tumors if treatment is started early in the stage of retinal ganglion cell (RGC) dysfunction (Table 3). The correlation between tumor size and the postoperative MD has been a topic of debate (8,9). In this study, the max diameter of the tumor significantly correlated with postoperative MD in multivariable regression but not in univariable regression. However, after excluding 2 eyes with maximum tumor diameter greater than 40 mm as outliners, the maximum tumor diameter did not correlate with postoperative MD in both multivariable and univariable regression analyses (Sup. Table 1, http://links.lww.com/WNO/ A638). The results were different in multivariable and in univariable regression analyses. As mentioned earlier, the size and change in the MD of cystic tumors tended to be larger than that of solid tumors in this study. Because half of the cases involved cystic tumors in this study, the larger size of these tumors may have resulted in better results in multiple regression analysis for postoperative MD. The cpRNFLT showed a stronger correlation with postoperative MD (P , 0.001, see Supplemental Digital Content, Figure 1A, http://links.lww.com/WNO/A638) than with preoperative MD (P = 0.004, see Supplemental Digital Content, Figure 1B, http://links.lww.com/WNO/ A638). However, the cpRNFLT did not significantly correlate with the operative change in MD in this study. The preoperative visual field deficiency reflects both degenerated RGCs and surviving but dysfunctional RGCs. Even when retinal nerve fibers are injured by laser-induced axotomy, the structural changes caused by retrograde degeneration occurred over 4 weeks (16). Another good example is traumatic optic neuropathy (17,18), in which the optic atrophy appears sometime after the injury and progresses over approximately 1 month after the injury. Unlike laserIto et al: J Neuro-Ophthalmol 2023; 43: 376-382 induced axotomy or traumatic optic neuropathy, the irreversible axonal degeneration caused by the compression of pituitary tumors will take more time, indicating that surviving but dysfunctional RGCs may exist in patients with progressive pituitary tumors compressing the optic chiasm. However, in contrast to the preoperative MD, a reduction in the cpRNFLT reflects only degenerated RGCs that occur as a result of irreversible loss of nerve fibers (3). Although the function of the surviving but dysfunctional RGCs may be restored by releasing the compression, the function of the degenerated RGCs is not restored after the surgery. Thus, both the reduction in cpRNFLT and postoperative visual field defect reflect only degenerated RGCs, which is why cpRNFLT was more significantly correlated with postoperative MD than with preoperative MD and the change in MD. This study had several limitations. First, because we could only collect the data for 32 eyes of 18 patients, the sample size was too small to detect statistically significant differences. This study was also retrospective in nature. In particular, the interval between the surgery and the postoperative visual field test varied. However, this interval did not significantly correlate with the magnitude of MD change after the surgery. Second, the cpRNFLT reduction does not directly reflect the loss of RGCs. A previous study reported that ganglion cell complex (GCC) measurements were significantly correlated with postoperative MD better than with cpRNFLT(19). In addition, measurement of GCC by OCT can make it easier to detect macular changes with vertical step (20). Analysis of GCC may also reveal the correlation between preoperative changes detected by OCT and the perioperative course of visual acuity. We did not take into account the interval between appearance of symptoms and the surgery. CONCLUSIONS Cystic tumors enlarge more rapidly than solid tumors. The visual field in patients with cystic tumors showed significantly greater improvements than that in patients with solid tumors. STATEMENT OF AUTHORSHIP Conception and design: M. Ito, K. Suda; Acquisition of data: M. Ito, K. Suda, E. Nakano, M. Tagawa; Analysis and interpretation of data: M. Ito, K. Suda. Drafting the manuscript: M. Ito, K. Suda, E. Nakano, M. Tagawa; Revising the manuscript for intellectual content: all authors. Final approval of the completed manuscript: All authors. ACKNOWLEDGMENTS The authors thank Dr. Masaki Nishimura (Department of Neurosurgery, Fukui Red Cross Hospital, Fukui, Japan) and Dr. Masato Hojo (Shiga General Hospital, Shiga, 381 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Original Contribution Japan) for their support as neurosurgeons in charge of the subjects in the current study. REFERENCES 1. Zhang J, Zhang S, Song Y, Zhu C, He M, Ren Q, Shan B, Wang Z, Zeng Y, Xu J. Predictive value of preoperative retinal nerve fiber layer thickness for postoperative visual recovery in patients with chiasmal compression. Oncotarget. 2017;8:59148–59155. 2. Laws ER, Trautmann JC, Hollenhorst RW. 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