Initial Clinical Observational Analysis of outer retinal corrugations Changes and Reattachment Morphology in Rhegmatogenous Retinal Detachment Based on SD-OCT

doi:10.21203/rs.3.rs-4829470/v1

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Initial Clinical Observational Analysis of outer retinal corrugations Changes and Reattachment Morphology in Rhegmatogenous Retinal Detachment Based on SD-OCT

https://doi.org/10.21203/rs.3.rs-4829470/v1

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Objective: To observe and summarize the reattachment morphological features of outer retinal corrugations (ORC) in rhegmatogenous retinal detachment (RRD) using SD-OCT, providing new evidence for the diagnosis and treatment of retinal detachment surgery.

Methods: A retrospective analysis was conducted on the clinical data of 64 patients with rhegmatogenous retinal detachment who were treated between March 2020 and March 2024. All participants were monitored preoperatively and postoperatively at 1 week, 1 month, and 3 months. Measurements included best-corrected visual acuity (BCVA) (converted to LogMAR visual acuity from the standard logarithmic visual acuity chart), fundus examination under mydriasis, and spectral domain optical coherence tomography (SD-OCT) based on spectral interferometry. The study observed and summarized the structural characteristics of the ORC under SD-OCT and postoperative changes in the outer retinal folds (ORF).

Results: A total of 64 eyes had no ORC related manifestations in≤4 and≥42 days, and most of the patients in the middle region were complicated with ORC structural changes (46 / 53; 87%). In the 51 patients involving the macula, the mean visual acuity of patients without ORF structural changes 1 week and 1 month after surgery was better than the group with ORF. There was no significant difference (P> 0.05); The incidence of postoperative ORF in patients with preoperative ORC findings is approximately 60.9%, significant difference compared with patients without preoperative ORC performance (P <0.05); Summarize the three reduction morphological manifestations of ORC, 22 patients / type ORC had no ORF morphology after reduction, The rest are combined with abnormal reduction morphology (21 / 22), However, 24 patients with type I ORC had 6 had abnormal ORF morphology (6 / 24), There was statistical significance (P <0.05); Among the patients with preoperative ORC findings, There were no statistical differences in postoperative ORF performance comparisons among patients with different surgical methods.

Conclusion: SD-OCT can clearly display the morphological characteristics of ave-like changes in the peripheral retina associated with rhegmatogenous retinal detachment. Postoperative retinal detachment with abnormal ORC is more likely to show ORF changes. Type I ORC has a better prognosis compared to Types II/III, and some retinal detachment cases in Type I can recover to a normal shape during the repositioning process.

Peripheral retinal wave-like changes

Retinal outer layer folding

Spectral-domain optical coherence tomography (SD-OCT)

Rhegmatogenous retinal detachment

Rhegmatogenous retinal detachment (RRD) is caused by retinal thinning or degeneration leading to a retinal neuroepithelial tear due to vitreous traction. Degenerative vitreous or liquefied vitreous enters the subretinal space through the tear, causing retinal detachment. Scleral buckle (SB) and pars plana vitrectomy (PPV) are common treatment methods, and some patients may also be treated with gas or inert gas tamponade. OCT provides significant advantages in observing macular structure or detachment sites post-surgery. Current research often focuses on the relationship between retinal microstructural changes and visual function recovery, particularly in anatomical repositioning of retinal detachment. Ideally, this includes observing the presence of external membrane discontinuity, ellipsoid zone defects, secondary proliferative membranes, and macular edema. Among these, outer retinal folds (ORF) are considered an important structural healing factor, with corresponding outer retinal corrugations (ORC) potentially causing retinal photoreceptor contact, affecting retinal structural healing. Understanding the pathophysiological mechanisms of ORC formation is crucial for improving the integrity of retinal attachment structures. This paper aims to use SD-OCT to observe and summarize different ORC presentations and repositioning morphologies in rhegmatogenous retinal detachment, providing new evidence for the diagnosis and treatment of retinal detachment surgery.

A retrospective analysis was conducted on 64 patients with rhegmatogenous retinal detachment who visited between March 2020 and March 2024. Among them, 65% (39 patients) were male, with ages ranging from 19 to 70 years (mean age: 45.3±15.7 SD). The average duration of retinal detachment was 16.6±13.5 SD days (range: 1-78 days). The surgical methods varied and were categorized as follows: Scleral Buckle (SB) in 17 cases, Pars Plana Vitrectomy (PPV) in 44 cases, and SB+PPV in 3 cases. Exclusion criteria:Any ocular disease affecting the posterior segment that could influence observations；Any eye disease including severe ocular trauma, history of intraocular or refractive surgery, or any condition potentially affecting the optic nerve head or optic nerve canal.；Any pathological eye disease that could potentially lead to vision impairment；Glaucoma (with abnormal visual field tests) or intraocular pressure (IOP)>21mmHg；Inflammatory, infectious, or ischemic diseases.

Table 1: General Information and Characteristics of Patients [Number (%)]

	[Number(%)]		[Number(%)]
Age (y)		Macular involvement
≤40	24（37.5）	with	51（79.7）
＞40	40（62.5）	None	13（20.3）
Time of onset (d)		Preoperative ORC characteristics
≤7	16（25.0）	Present	46（71.9）
8-30	38（59.3）	Absent	18（28.1）
≥30	10（29.7）	postoperative ORF features
Gender		Folding(Present)	29（45.3）
Male	39（60.9）	Unfolded(Absent)	35（54.7）
Female	25（39.1）	Other abnormal manifestations
Tear location		ORC adhesion	22（47.8）
Superior	34（53.1）	Heavy water residue	4（6.2）
Inferior	20（31.3）	macular hole	2（3.1）
Both Superior and Inferior	10（125.6）	Postoperative outer layer atrophy	6（9.4）
Tear size（PD）		Range of retinal detachment under SLO (hour)
≤1	39（60.9）	≤6	8（12.5）
＞1-＜3	22（34.4）	＞6-＜12	35（54.7）
≥3	3（4.7）	≥12	21（32.8）

All subjects underwent the following preoperative examinations:slit-lamp microscopy, best-corrected visual acuity (BCVA) measurement (using a standard logarithmic visual acuity chart converted to LogMAR visual acuity), dilated fundus examination, and intraocular pressure measurement. Preoperative, immediate postoperative, one-month, and three-month postoperative examinations included spectral-domain optical coherence tomography (SD-OCT) using the Spectralis HRA+OCT system from Heidelberg Engineering, Inc, Heidelberg, Germany. These were performed by the same experienced ophthalmologist and independently verified by another physician. Examination parameters included selecting the retinal detachment and macular regions with a 6mm×6mm multi-line scan mode, capturing the best images for further analysis.

OCT observations:Detailed identification of ORC structural characteristics and postoperative ORF changes in the same plane were conducted. Fundus scanning laser examination was performed using the OPTOS Daytona laser scanning ophthalmoscope. These examinations are summarized in Table 1.Comparison of basic data between the two groups:There were no statistically significant differences (P > 0.05), indicating comparability. All patients understood the study's content and purpose. All study procedures adhered to the principles of the Declaration of Helsinki. All patients understood the study's content and purpose. All study procedures adhered to the principles of the Declaration of Helsinki. This study was approved by the Ethics Committee of the Second Affiliated Hospital of Zunyi Medical University, and all subjects signed informed consent forms.

Statistical analysis:Descriptive statistical data were expressed as mean (x) and standard deviation (SD). Normality of data distribution was tested. For normally distributed data, independent sample t-tests were used for comparisons between two groups; for non-normally distributed data, Mann-Whitney U tests were employed. Categorical data were expressed as rates (%) and analyzed using Chi-square tests. When the expected count was less than 5 or the sample size was less than 40, Fisher’s exact test was used. A P-value of less than 0.05 was considered statistically significant. All analyses were performed using SPSS 29.0 statistical software.

SD-OCT assessment of the clinical characteristics of ORC and ORF are detailed in Table 1. The primary retinal reattachment success rate was 92.2% (59/64). Among these, three cases did not achieve anatomical reattachment after PPV: one case was found to have a missed tear in another quadrant during the second surgery, and two cases had retinal anterior proliferative traction. Additionally, two cases did not heal after SB surgery and subsequently underwent PPV in the second stage.

The preoperative average visual acuity (Log MAR) was 1.61 ± 0.98, and at one week postoperatively, it was 0.84 ± 0.46. At one month postoperatively, it improved to 0.56 ± 0.31. The differences between preoperative and postoperative visual acuity were statistically significant (P < 0.05).

Among the 51 patients with macula involvement, the average visual acuity at one week and one month postoperatively in patients without ORF structural changes was better than that in the ORF group, but this difference was not statistically significant (P > 0.05), as shown in Table 2.

Table 2:Comparison of Preoperative and Postoperative BCVA(x±s,logMAR)in 51 Cases(Macula Involvement)with and without ORF Characteristics

Group	Cases	BVCA
Group	Cases	Preoperative	1 Week Postoperative	1 Month Postoperative
With ORF	24	2.05±0.91^a	0.97±0.47	0.69±0.34
Without ORF	27	1.72±0.89^ab	0.85±0.32^b	0.54±0.21^b

^a:Significant difference between preoperative and postoperative(1 week and 1 month)(P<0.05).

^b:No significant difference within the group(P>0.05).

With the extension of retinal detachment duration, we found that in cases with a disease course of ≤4 days (8/64; 12.5%) and ≥42 days (3/64; 4.7%), there were no ORC-related manifestations. Most patients in the intermediate duration group exhibited ORC structural changes (46/53; 87%). Additionally, among patients with no ORC structure preoperatively, only 1 out of 18 (5.6%) exhibited ORF postoperatively. However, the incidence of postoperative ORF was approximately 60.9% (28/46) in patients with preoperative ORC, a statistically significant difference (P < 0.05), suggesting a causal relationship between postoperative ORF and ORC.

For the 35 patients with preoperative ORC undergoing PPV surgery, 15 had no ORF postoperatively (40.0%). Among the 8 patients with preoperative ORC undergoing SB surgery, 3 had no ORF postoperatively (37.5%). All three patients who underwent combined surgery had postoperative ORF. These differences were not statistically significant, as shown in Table 3.

Summary of ORC OCT presentations:

Type I: Smaller outer retinal folds without high-reflective lesions inside (24/46; 52.2%).

Type II: Smaller outer retinal folds with dot-like high-reflective lesions inside, leading to subretinal "hill-like" elevations later (20/46; 43.5%).

Type III: Larger outer retinal folds, often showing ORC adhesion preoperatively and subretinal "carpet-like" high reflectivity postoperatively, sometimes with localized elevations (2/46; 4.3%).

The average tear size in patients with ORC was 1.33 ± 1.28 PD, compared to 1.37 ± 1.36 PD in patients without ORC, showing no statistical difference (P > 0.05). The average extent of retinal detachment in patients with ORC was 10.63 ± 3.84 hours, compared to 9.33 ± 4.32 hours in patients without ORC, also showing no statistical difference (P > 0.05).

Among the 22 patients with Type II/III ORC, only one patient had no ORF morphological abnormalities after reattachment, while the rest had reattachment abnormalities (21/22). Among the 24 patients with Type I ORC, 6 had ORF morphological abnormalities after reattachment (6/24). The differences between these groups were statistically significant (P < 0.05), as shown in Table 4.

All SB patients underwent external scleral drainage during surgery, and 2 patients also had vitreous cavity gas injection (sterile air). All PPV procedures used silicone oil tamponade. Among the 3 patients who underwent combined surgery, 2 had larger outer retinal folds and 2 had macular hole-type retinal detachment. In the latter cases, the OCT showed faint connections in the outer layer structure under the hole, with the macular hole closing postoperatively and atrophy of the outer retinal structure under the fovea.

Table 3: Comparison of ORF and ORC Characteristics and Surgical Methods under SD-OCT

Group	Cases	Postoperative ORF (Cases,%)		Group	Cases	Surgical Method(Preoperative ORC Present)
Group	Cases	Without	With	Group	Cases	PPV	SB	PPV+SB
With ORC	18	17（94.4）	1（5.6）	Postoperative With ORF	26	20^a（72.4）	3^a（17.2）	3^a（10.3）
Withou ORC	46	18（39.1）	28（60.9）	Postoperative Without ORF	30	15^a（86.7）	5^a（13.3）	0^a（0）
х2	15.974			Fisher’s value	3.084
P	＜0.001			P	0.234

Bonferroni multiple comparison method:^a indicates no significant difference betweengroups (P>0.05).

Table 4:Comparison of Different Types of ORC Reattachment Morphologies

Group	Cases	ORC Type
Group	Cases	l	ll	IIl
With ORF	27	6^a	19^b	3^b
Without ORF	19	18^a	1^b	0^b
Fisher’s value	25.284
P	＜0.001

Bonferroni multiple comparison method:^aindicates significant difference betweengroups (P<0.05);b indicates no significant difference between groups (P>0.05).

The anatomical reattachment of the retina has always been a focal point of research. Many studies have focused on observing structures such as spontaneous retinal displacement under fundus autofluorescence, continuity of the ellipsoid zone and external limiting membrane (ELM) under OCT, secondary epiretinal membrane, and cystoid macular edema [1-3]. However, changes in the ORC structure during retinal detachment have received little attention. Ooto et al. [4]first summarized the structure known as "ORC," finding that in AMD patients, high-reflective corrugations on the outer retina over areas of RPE/Bruch’s membrane atrophy, possibly related to subretinal fluid and compensatory CNV formation, were visible only in regions associated with CNV or GA.

Other studies have found similar deposits in patients with late-onset RP and Sorsby's fundus dystrophy, where the deposition band is believed to impair nutrient transport to the inner retina [5,6]. The pathophysiology of ORC involves the loss of RPE regulation over subretinal fluid and retinal homeostasis. Some researchers have suggested that this might be due to differences in the physicochemical properties of the exudate [6]. In our observations, no ORC-like changes were found in exudative diseases such as VKH and CSC.

Previous theories have suggested that the longer the duration of retinal detachment, the poorer the visual function recovery after reattachment. However, summarizing the recovery mechanism of ORC, when the retinal tear is closed, the function of the RPE improves to balance the exchange of nutrients between the outer retina and the subretinal fluid (SRF). Through the RPE's promotion of SRF absorption, the recovery of the outer structure and the smooth reattachment of the detached retina are more likely to meet the requirements for anatomical reattachment. The more accepted mechanism of ORF is the misaligned healing between the retinal photoreceptors and the RPE. Observing different degrees of ORF cases, some cases, despite showing ORC, have good alignment during recovery or retain small retinal folds, with only high-reflective points on the RPE later on (considered to be local outer segment photoreceptor adhesion followed by subretinal fibrosis and RPE proliferation).

Additionally, an important change we observed is that in the case of retinal detachment, there are more noticeable adhesions between some wave-like structures in the ORC. The formation mechanism is similar to the connections between photoreceptors and the inner and outer segments of surrounding photoreceptors, mainly involving the myoid zone, ellipsoid zone, and inner segments of the photoreceptors [7]. According to OCT observations, such structures are difficult to restore during PPV or SB surgery, eventually forming typical ORF. This retinal structure misalignment ultimately leads to pigment migration, proliferation, or atrophy. It is unclear whether this structure is highly correlated with subretinal proliferative changes. Preoperative and postoperative OCT comparisons of this structure are important, but it is unknown whether RPE regulation can improve such adhesions.

Moreover, in PPV patients, such structural changes need to be differentiated from subretinal heavy droplet residues, which appear as a vertical elliptical subretinal cyst-like change with smooth boundaries and long-term structural stability. It is also necessary to distinguish this from full-thickness retinal folds, which result from the passive compression of the originally curved retina in the vitreous cavity after detachment, essentially a compression change in the tissue [8].

Based on our case observations, Type I ORC has a better prognosis compared to Types II and III. In Type I, some reattachment morphology can normalize during recovery. It is unclear whether this correction of simple point-to-point misalignment between the retina and RPE is regulated by RPE or corrected by the recovery of the elastic modulus of the outer retina. This aligns with the findings of Muni RH et al. [9], who concluded that during reattachment, ORC at the edge of the attachment has a tendency to gradually flatten. Types II and III ORC are considered to involve varying degrees of outer segment photoreceptor adhesion, which affects postoperative retinal flattening and reattachment.

Regarding the course of retinal detachment, patients with a duration of ≤4 days did not exhibit ORC, which might be a conditional factor for ORC formation. This change does not occur immediately after detachment, suggesting that early changes in the subretinal fluid environment might have a time constraint on the formation of ORC in the outer retinal layers. Among patients with a course of >4 days, 87% exhibited ORC. In a small subset of patients without ORC, this indicates that under natural conditions, some ORC structures may spontaneously recover or may not develop ORC changes at all. Even some patients with calcification-like changes in the outer segments or stable outer structures (without ORC) before surgery can achieve good structural recovery post-repair.

Evaluating the reasons for structural recovery in these patients could provide guidance for treating retinal detachment patients with ORC. Further research is needed to summarize the recovery time and conditions for Type I ORC. It is important to note that excessively prolonging retinal reattachment time is also detrimental to anatomical recovery, potentially leading to atrophy of the photoreceptor outer segments and RPE. Providing the outer retinal layer with time for physiological morphological recovery and balance with the RPE might be more beneficial for anatomical reattachment.

Preoperatively significant ORC, subretinal fluid drainage, and assisted reattachment techniques might prevent timely recovery of ORC. In this scenario, the elastic modulus between the inner and outer retinal layers may differ, leading to potential reattachment outcomes: 1) point-to-point misalignment healing, resulting in retinal folds; or 2) inability to smooth out the outer retinal folds, resulting in long-term local irreversible damage to the ellipsoid zone, IS/OS, and RPE [10].

Based on Dalvin's theory of hydration in ORC formation [11], subretinal fluid in rhegmatogenous retinal detachment (RRD) is essentially liquefied vitreous. The structural basis of the wavy outer plexiform layer lies in the differential hydration effects on the interstitial matrix of outer retinal photoreceptors compared to the inner retina, leading to the folding of the outer retina and potentially resulting in compensatory ORC formation. However, we propose that the occurrence of structural factors causing differences in the elastic modulus between the inner and outer retinal layers post-detachment fundamentally stems from the inherent structural differences between the inner and outer retinal tissues. These differences include variations in vascular density, cellular composition (e.g., retinal ganglion cells (RGC) vs. photoreceptors), and the asymmetric distribution of Müller cell endfeet [12-14].

Future research should employ elasticity models to analyze factors contributing to ORC structure recovery and summarize changes in the elastic modulus of ORC at different stages of the disease. This approach could provide better guidance for surgical interventions in retinal detachment. One limitation of this study is the constraint imposed by the use of SD-OCT. Ultra-widefield swept-source optical coherence tomography angiography (UWF SS-OCTA) could be more beneficial for in-depth observation and analysis of changes in the ORC recovery process. Moreover, extending the observation period for ORC and ORF is necessary to analyze their progression and structural changes comprehensively.

Acknowledgements

Not applicable.

Authors contribution

Guo Wenjun provided study concept and design, manuscript drafting, and critical manuscript revision. Li Mingbo provided study concept and design, critical revision of the manuscript for important intellectual content, and critical revision of the manuscript. Liu Youli provided screening articles, writing the original manuscript, revising and editing the manuscript, figure preparation, and preparing the final draft. Nie Xiaomei contributed to writing the original draft and reviewed the revised version. SSH contributed to writing the original draft and reviewed the revised version.Guo Wenjun performed the study concept, design, and review of the revised version. Su Gang provided screening articles, writing the original manuscript, revising and editing the manuscript, and preparing the final draft. All authors read and approved the final revised version of the manuscript.

Funding

1.Science and Technology Fund of Guizhou Provincial Health Commission (gzwkj2023-434)

2.Science and Technology Program of Guizhou Province，Basic Research of Qiankehe（No. ZK[2023]-529）

Availability of data and materials

The datasets used in the current study are available upon reasonable request.

Ethics approval and consent to participate

All patients understood the study's content and purpose. All study procedures adhered to the principles of the Declaration of Helsinki. All patients understood the study's content and purpose. All study procedures adhered to the principles of the Declaration of Helsinki. This study was approved by the Ethics Committee of the Second Affiliated Hospital of Zunyi Medical University, and all subjects signed informed consent forms.

Consent for publication

Figures are original and unpublished before. Our patients gave written informed consent for their personal or clinical details along with any identifying images to be published in this study.

Competing interests

The authors declare no competing interests.

Author details

Ophthalmology Department of the Second Affiliated Hospital of Zunyi Medical University,Zunyi,Guizhou Province,Zip Code: 563000,China.

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Initial Clinical Observational Analysis of outer retinal corrugations Changes and Reattachment Morphology in Rhegmatogenous Retinal Detachment Based on SD-OCT

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