
==== Front
Medicine (Baltimore)
Medicine (Baltimore)
MD
Medicine
0025-7974
1536-5964
Lippincott Williams & Wilkins Hagerstown, MD

MD-D-24-06495
00026
10.1097/MD.0000000000039588
3
5800
Research Article
Observational Study
The impact of postoperative nasal oxygen therapy on early-stage corneal edema in cataract patients with dynamic Scheimpflug analyze: A retrospective study
Dong Guangguo MD sydongsir@163.com
a
https://orcid.org/0009-0005-1954-2402
Hao Zhongkai MD haozhongkai2014@163.com
ab
https://orcid.org/0000-0001-5357-5711
Zhang Chenming MD, PhD ab*
Deng Aijun MD, PhD dengaijun@hotmail.com
b
a Department of Ophthalmology, Jinan Second People’s Hospital, Jinan, China
b Department of Ophthalmology, School of Clinical Medicine, Weifang Medical University, Weifang, China.
* Correspondence: Chenming Zhang, Department of Ophthalmology, Jinan Second People’s Hospital, Jinan 250200, China (e-mail: chenming-zhang@163.com).
13 9 2024
13 9 2024
103 37 e3958815 6 2024
08 8 2024
15 8 2024
Copyright © 2024 the Author(s). Published by Wolters Kluwer Health, Inc.
2024
https://creativecommons.org/licenses/by-nc/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial License 4.0 (CCBY-NC), where it is permissible to download, share, remix, transform, and buildup the work provided it is properly cited. The work cannot be used commercially without permission from the journal.

This study aimed to assess the impact of 6 hours of postoperative nasal oxygen therapy on early-stage corneal edema in patients with nuclear cataracts of grades 3 to 4. A retrospective study involved 49 patients (49 eyes) with grades 3 to 4 nuclear cataracts undergoing phacoemulsification and intraocular lens implantation from September 2021 to September 2022. The oxygen group (27 cases) received postoperative nasal oxygen therapy for 6 hours, while the control group (22 cases) received no additional treatment. Corneal edema was evaluated 24 hours postoperatively using a slit lamp microscope, recording the edema degree. The Pentacam anterior segment analyzer measured central corneal thickness (CCT), corneal volume (CV), and corneal optical density (COD) values preoperatively and 24 hours postoperatively. The study enrolled 49 patients. Preoperatively, there were no significant differences between the 2 groups. The oxygen group and the control group exhibited significant differences in CCT, CV, and corneal optical density values before and after surgery for intragroup comparison (all P < .05). At 24 hours postoperatively, the proportion of grade 0 corneal edema in the oxygen therapy group was 59.3%, compared to 31.8% in the control group, with no statistically significant difference (P > .05). The postoperative logMAR visual acuity in the oxygen therapy group was 0.0969 (0.0969, 0.2218), and in the control group it was 0.0969 (0.2218, 0.3979), with a statistically significant difference (P < .05). In oxygen group, the CCT, CV were 585.00 (553.00, 604.00), 68.0 (61.9, 71.3) respectively, all significantly lower than 603.50 (578.50, 788.25), 73.05 (65.3, 75.73) (all P < .05). Statistically significant differences were found in overall COD, COD within specific depth and thickness ranges, and COD within the anterior layer (120 μm thickness) at 24 hours postoperatively (all P < .05). No significant difference was observed in COD values within the central and posterior layers (60 μm thickness) between the 2 groups (all P > .05). Postoperative nasal oxygen therapy for 6 hours immediately after surgery could alleviate the severity of early-stage corneal edema in patients with nuclear cataracts of grades 3 to 4.

corneal edema
corneal endothelial injury
corneal optical density
nasal oxygen therapy
phacoemulsification
Jinan Science and Technology Bureau 10.13039/100007785 202225058 Chenming ZhangOPEN-ACCESSTRUE
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pmc1. Introduction

Age-related cataract stands as a leading cause of visual impairment among the elderly. The most efficacious surgical approach for cataract treatment involves phacoemulsification combined with intraocular lens implantation.[1] Presently, cataract interventions are characterized by a high patient volume, brief surgical durations, and minimal postoperative complications. The growing awareness of health issues and advancements in cataract surgery techniques have led to an increasing preference for daytime surgeries among individuals. This shift necessitates heightened vigilance from surgeons regarding early postoperative complications associated with cataracts.[2]

Patients with nuclear cataracts of grades 3 to 4 face an elevated risk of corneal endothelial cell damage during surgery, leading to postoperative corneal edema. Inadequate management poses the threat of severe complications, such as corneal endothelial decompensation.[3] Although corneal edema induced by phacoemulsification cataract surgery is typically mild, its detection under a slit lamp microscope can be challenging in some cases. Even in the absence of observable corneal edema, patients may experience visual discomfort. Subtle corneal edema has the potential to elevate corneal astigmatism, causing intraocular light scattering and glare, ultimately contributing to compromised visual perception. Therefore, diligent early postoperative monitoring of corneal conditions is imperative.[4]

In recent years, numerous studies have employed central corneal thickness (CCT) and corneal volume (CV) as key indicators of subclinical corneal edema.[5,6] Earlier investigations[7,8] propose that the Pentacam anterior segment analyzer, employing light-density measurement methods, offers an objective means to quantify corneal edema. In their study, Sho Ishikawa et al[9] have illustrated the effectiveness of corneal optical density (COD) values in quantitatively analyzing corneal edema, which might go unnoticed under a slit lamp microscope.

Corneal transparency hinges on the pump function of corneal endothelial cells, primarily regulated by oxygen-dependent sodium-potassium adenosine triphosphatase activity.[10,11] Oxygen, essential for this process, is derived from the atmosphere, limbal vessels, and aqueous humor.[12] Damage to corneal endothelial cells during phacoemulsification reduces the number of cells with normal pump function, leading to inadequate moisture pumping from the stroma into the aqueous humor. This stromal moisture retention increases CCT and CV, lengthening the distance for oxygen to reach the corneal endothelial cell layer, intensifying the hypoxic state, and further compromising pump function.[10]

We hypothesized that postoperative nasal oxygen supplementation in patients could enhance systemic blood oxygen saturation. By increasing oxygen levels in blood vessels surrounding the cornea and in the aqueous humor, our goal was to provide additional oxygen to corneal endothelial cells. This intervention aimed to enhance the functionality of corneal endothelial cells and alleviate postoperative corneal edema. In our study, we administered postoperative nasal oxygen therapy for 6 hours to patients with grades 3 to 4 nuclear cataracts. Our findings suggested that nasal oxygen therapy could partially mitigate the severity of postoperative corneal edema, as detailed below.

2. Materials and methods

2.1. General information

The study comprised 49 eyes from eligible patients meeting inclusion criteria with complete data. This research follows the declaration of Helsinki, the consent of the Jinan Second People’s Hospital of Medical Ethics will be approved. All patients were informed consent, and sign the informed consent.

2.2. Inclusion and exclusion criteria

The inclusion criteria were as follows: (1) patients with age-related cataracts, excluding those with traumatic and pseudo-exfoliative cataracts; (2) individuals undergoing phacoemulsification cataract extraction combined with intraocular lens implantation for the first time; (3) preoperative nuclear hardness grading of 3 to 4; (4) corneal endothelial cell density of 2000 to 2500 cells/mm2 or above; (5) absence of other ocular diseases.

The exclusion criteria were as follows: (1) eyes with a history of other surgeries; (2) anterior chamber depth < 2.5 mm or a predisposition to glaucoma; (3) patients with a history of chronic respiratory disease such as chronic obstructive pulmonary disease, etc; (4) patients with a history of chronic diseases such as hypertension, diabetes, etc; (5) patients with systemic immune disorders, including Sjögren’s syndrome, rheumatoid arthritis, etc; (6) Patients who experienced severe complications during surgery, such as desmeme membrane detachment, iris trauma, and posterior capsule rupture, etc; (7) contraindications to nasal oxygen therapy.

2.3. Grouping strategy

Participants were randomly allocated to either the oxygen group (27 eyes) or the control group (22 eyes) using a computer-generated randomization list, which was created prior to the study initiation and concealed from the investigators until the point of assignment. The oxygen group received postoperative nasal oxygen therapy for 6 hours (oxygen flow rate: 3L/min; oxygen concentration: 100%), while the control group received no additional treatment. All patients received tobramycin/dexamethasone eye ointment postoperatively, and bandages were removed 24 hours after surgery.

2.4. Surgical procedure

All surgeries were conducted by the same experienced cataract specialist using standardized phacoemulsification combined with intraocular lens implantation. The Centurion phacoemulsification system (Alcon, Fort Worth, TX) was employed with the following parameters: fluid flow and aspiration rate set at 40 mL/minute, vacuum pressure at 400 mm Hg, energy level at 50%, and intraocular pressure at 85 cm H2O. A 2.8 mm wide tunnel incision was made at the 11:00 position on the transparent corneal margin, and a side incision was made at the 2:00 position. Viscoelastic (Provisc, Alcon, Fort Worth, TX) was injected into the anterior chamber, followed by continuous circular tearing of the capsulorhexis. Ultrasound was utilized to emulsify the lens cortex and nucleus, and after residual cortex aspiration, a foldable intraocular lens was implanted into the capsular bag, followed by watertight incision closure. The intraoperative average ultrasonic power and effective ultrasound time was recorded.

2.5. Evaluation indices

This study was designed to have 22 patients per group so as to achieve 80% power to detect a 20% difference in SVR rates (40% vs 60%), at the 5% level of significance. The severity of corneal edema was assessed 24 hours postoperatively using a slit lamp microscope (Carl Zeiss, Oberkochen), and the grading followed the criteria established by Kausar et al.[13] Measurements of CCT, CV, and COD values at various diameter and thickness ranges were conducted before and 24 hours after surgery using the Pentacam anterior segment analyzer (Oculus, Wetzlar, Germany). Participants were randomly allocated to either the oxygen group or the control group in a manner that ensured both the assessors and the independent evaluators performing the grading of corneal edema were blinded to the group assignments.

2.6. Statistical analysis

Statistical analysis utilized SPSS 26.0 software. The data were represented using mean ± standard deviation in accordance with a normal distribution. For inter-group comparison of measurement data, an independent sample t-test was employed, while a paired sample t-test was used for intragroup comparison. The median (P25, P75) was utilized to represent non-normally distributed data. Mann–Whitney U test was conducted to compare measurement data between groups, and the Wilcoxon coincidence rank test was employed for intragroup comparison. Inter-group comparisons of count data were conducted using Chi-square tests. The significance level was set at α = 0.05.

3. Results

3.1. Comparison of general information between the 2 groups

No statistically significant differences were found in age, gender, eye laterality, corneal endothelial cell density, anterior chamber depth, nuclear hardness grading, and arterial oxygen saturation between the oxygen group and the control group (all P > .05). Additionally, there were no statistically significant differences in average ultrasound energy and average effective ultrasound time during surgery between the 2 groups (all P > .05) (Table 1).

Table 1 Comparison of general characteristics between the 2 groups.

Item	Oxygen group	Control group	P	
Age (year)	62.93 ± 2.24	62.86 ± 2.32	0.985*	
Male (case)	13 (48.1%)	11 (50%)	0.897**	
Right eye (case)	12 (44.4%)	10 (45.5%)	0.944**	
Pre-operation	
Corneal endothelial cell density (mm2)	2837.04 ± 145.55	2842.32 ± 159.73	0.904*	
Anterior Layer Thickness (mm)	2.84 ± 0.08	2091 ± 0.11	0.565*	
Lens hardness (emery grade 4)	7 (25.9%)	6 (27.3%)	0.915**	
Arterial oxygen saturation (%)	0.98 ± 0.01	0.98 ± 0.01	0.614*	
Intra-operation	
Average ultrasound energy (%)	22.89 ± 1.88	22.84 ± 1.52	0.923*	
Average effective time (s)	16.07 ± 0.28	16.56 ± 0.33	0.260*	
* Indicates the P-value from an independent samples t-test.

** Indicates the P-value from a Chi-square test.

3.2. Comparison of postoperative visual acuity between the 2 groups

Twenty-four hours postoperatively, there were statistically significant differences in postoperative visual acuity between the 2 groups (P = .046) (Table 2).

Table 2 Comparison of postoperative visual acuity between the 2 groups.

Group	Postoperative 24 hours (μm)	
Oxygen group	0.0969 (0.0969,0.2218)	
Control group	0.0969 (0.2218,0.3979)	
z	‐1.997	
P	.046	

3.3. Comparison of postoperative corneal edema grading under slit lamp microscopy between the 2 groups

By using the Chi-square test, χ2 = 3.665, P = .056 > .05, indicating no significant difference in the number of corneal edema grades between the 2 groups. Specifically, in the oxygen group, 59.3% had a corneal edema grade of 0, and 40.7% had a non-0 grade. In the control group, 31.8% had a grade of 0, and 68.2% had a non-0 grade (Table 3).

Table 3 Comparison of postoperative corneal edema grades between the 2 groups.

Group	Corneal edema grade (%)	Total	χ 2	P	
	0 grade (%)	Non-0 grade (%)		3.665	.056	
Oxygen group	16 (59.3)	11 (40.7)	27	
Control group	7 (31.8)	15 (68.2)	22	
Total	23	26	49	
Note: χ2 denotes the Chi-square statistic, and P represents the corresponding P-value.

3.4. Comparison of corneal endothelial cell density, CCT, and CV before and after surgery between the 2 groups

No statistically significant differences were observed in preoperative CCT and CV between the 2 groups (both P > .05). However, 24 hours postoperatively, there were statistically significant differences in both CCT and CV between the 2 groups (PCCT = 0.033, PCV = 0.017) (Table 4) (Fig. 1A and B).

Table 4 Comparison of CCT and CV before and 24 hours after surgery in 2 patient groups.

Group	CCT	CV	
Preoperative (μm)	Postoperative 24 hours (μm)	Preoperative (μm)	Postoperative 24 hours (μm)	
Oxygen group	538.00 (525.00,562.00)	585.00 (553.00,604.00)*	60.6 (58.2,62.5)	68.0 (61.9,71.3)*	
Control group	522.50 (505.75,573.00)	603.50 (578.50,788.25)*	59.75 (58.1,62.95)	73.05 (65.3,75.73)*	
P	.445	.033	.928	.017	
* Indicates a significant difference in the index before and 24 hours after the operation within the group (P < .05).

Figure 1. Comparison of corneal central thickness (CCT), corneal volume (CV), and corneal optical density (COD) in different diameter ranges and different thickness stratification ranges between oxygen inhalation group and control group at 24 hours after operation. *P < .05; Ns showed P > .05; D differential value.

3.5. Comparison of COD values before and after surgery between the 2 groups

3.5.1. Overall COD values before and after surgery in both groups

No statistically significant differences were found in preoperative overall COD values between the 2 groups (P > .05). However, 24 hours postoperatively, a statistically significant difference emerged in overall COD values between the 2 groups (P = .019) (Table 5) (Fig. 1C).

Table 5 Comparison of overall COD values before and 24 hours after surgery in 2 groups M(P25, P75).

Group	Preoperative (μm)	Postoperative 24 hours (μm)	
Oxygen group	16.4 (14.6,17.5)	18.1 (16.1,19.9)*	
Control group	16.8 (14.6,18.7)	20.5 (18.5,24.0)*	
P	.695	.019	
* Indicates a significant difference in the index before and 24 hours after the operation within the group (P < .05).

3.5.2. Comparison of COD values before and after surgery across different diameter ranges centered on the corneal apex

No statistically significant differences were observed in preoperative COD values within the 0 to 2 mm and 2 to 6 mm diameter ranges centered on the corneal apex between the 2 groups (both P > .05). However, 24 hours postoperatively, statistically significant differences emerged in COD values within the 0 to 2 mm and 2 to 6 mm diameter ranges centered on the corneal apex between the 2 groups (P0–2 mm = .048, P2–6 mm = 0.039) (Table 6) (Fig. 1D and E).

Table 6 Comparison of COD values within different diameter ranges centered on the corneal vertex before and 24 hours after surgery in 2 groups M(P25, P75).

Group	0–2 mm diameter range	2–6 mm diameter range	
Preoperative (μm)	Postoperative 24 hours (μm)	Preoperative (μm)	Postoperative 24 hours (μm)	
Oxygen group	13.2 (10.2,15.2)	13.6 (11.2,15.8)*	13.4 (11.2,15.3)	14.6 (11.7,16.4)*	
Control group	13.0 (10.2,14.6)	16.1 (12.8,19.2)*	13.2 (12.3,14.4)	16.5 (14.0,18.7)*	
P	.802	.048	.841	.039	
* Indicates a significant difference in the index before and 24 hours after the operation within the group (P < .05).

3.5.3. Comparison of COD values in different thickness layers between the 2 groups

No statistically significant differences were found in preoperative COD values within the anterior layer (120 μm thickness), central layer, and posterior layer (60 μm thickness) between the 2 groups (all P > .05). However, 24 hours postoperatively, a statistically significant difference emerged in COD values within the anterior layer (120 μm thickness) between the 2 groups (Panterior 120 μm = 0.037). However, no statistically significant differences were noted in COD values within the central layer and posterior layer (60 μm thickness) between the 2 groups (both P > .05) (Table 7) (Fig. 1F–H).

Table 7 Comparison of COD values within different thickness layers before and 24 hours after surgery in 2 groups M(P25, P75).

Group	Anterior layer (120 μm thickness)	Central layer	Posterior layer (60 μm thickness)	
Preoperative (μm)	Postoperative 24 hours (μm)	Preoperative (μm)	Postoperative 24 hours (μm)	Preoperative (μm)	Postoperative 24 hours (μm)	
Oxygen group	23.2 (19.5,26.3)	24.1 (22.4,27.2)*	14.5 (13.1,16.4)	15.2 (13.4,18.3)*	12.1 (9.5,15.3)	13.2 (11.4,17.2)*	
Control group	24.3 (19.9,26.8)	28.1 (24.6,33.0)*	15.1 (11.9,17.3)	16.6 (12.6,19.7)*	12.0 (10.0,13.7)	14.5 (12.3,16.4)*	
P	.849	.037	.755	.763	.748	.740	
* Indicates a significant difference in the index before and 24 hours after the operation within the group (P < .05).

4. Discussion

The increasing aging population has significantly elevated the incidence of age-related cataracts. Presently, phacoemulsification combined with intraocular lens implantation stands as the preferred and most effective surgical method for addressing age-related cataracts.[14] As living standards improve and health awareness increases, cataract surgery has become more minimally invasive and procedural, leading to a growing acceptance of daytime cataract surgery.[15] Concurrently, there is an escalating demand for favorable visual outcomes post-cataract surgery. Retrospective studies conducted by Lanchulev, Koolwijk, and others have affirmed the safety and effectiveness of cataract daytime surgery conducted by ophthalmologists without anesthesia support.[2,15] This approach allows patients to leave the hospital after a short observation period post-surgery, reducing hospitalization time and streamlining the inpatient process. However, it necessitates close attention from ophthalmologists to monitor the early-stage postoperative visual condition of patients and promptly address any complications arising from cataract surgery.

Despite the benefits of small incisions, rapid recovery, and reduced postoperative complications associated with phacoemulsification, various factors such as ultrasound energy, bubbles, irrigation fluid, and mechanical stress during surgery, particularly in direct contact with corneal endothelial cells, inevitably result in minor trauma to the eyes.[16] This trauma can impair the pump function of corneal endothelial cells, leading to corneal edema. In cases of severe damage, corneal endothelial decompensation may occur, potentially requiring corneal transplantation surgery. For patients with nuclear opacities of grade 3 to 4, surgeons often need to employ higher ultrasound energy and longer ultrasound time during phacoemulsification surgery. This elevated use increases the risk of corneal endothelial cell damage, heightening the likelihood of postoperative corneal edema. Therefore, early postoperative intervention is imperative to prevent the onset of severe complications.[17]

Maintaining corneal transparency hinges on the normal function of corneal endothelial cells, a single layer of flat cells.[18] Oxygen, a crucial factor, is essential for their proper functioning.[19] The Na-K-ATPase on their cell membranes actively pumps excess fluid from the stroma into the anterior chamber, a process vital for sustaining corneal transparency.[20] This ATP-dependent mechanism relies on mitochondrial metabolism, predominantly fueled by oxygen.[16] Studies reveal that the oxygen required by corneal endothelial cells primarily comes from 2 sources: passive diffusion through the cornea to the endothelial layer and supply from the vascular system at the corneoscleral limbus. A small amount is also provided by the aqueous humor.[21] After corneal endothelial cell damage, the reduced number of cells with normal pump function weakens their capacity to expel moisture from the stroma, resulting in stromal fluid retention and increased central stromal thickness. This leads to a prolonged distance for atmospheric oxygen to reach the corneal endothelial layer, inducing a hypoxic state. Nasal oxygen therapy, administered immediately postoperatively, significantly elevates the oxygen concentration in limbal vessels and the aqueous humor, which is pivotal for the metabolic activities of corneal endothelial cells.[22] The heightened oxygen availability not only augments mitochondrial respiration, leading to an upregulation of cellular energy production, but also modulates the expression of key genes involved in the corneal endothelial cell’s pump function. This, in turn, enhances the activity of the Na-K ATPase pump, accelerating the removal of excess fluid from the corneal stroma. Furthermore, the enriched oxygen environment may also attenuate the inflammatory response, which is known to exacerbate corneal edema, by reducing the production of pro-inflammatory cytokines and promoting the synthesis of anti-inflammatory mediators. Our hypothesis posited that immediate postoperative nasal oxygen therapy might mitigate the severity of postoperative corneal edema, preventing complications such as corneal decompensation. This intervention was particularly crucial for the early management of postoperative corneal edema.

Corneal edema has the potential to induce changes in CCT and CV. Previous studies have established that CCT and CV can serve as diagnostic indicators for subclinical corneal edema, offering a quantitative means to assess its degree.[23,24] In this study, we conducted comparisons of CCT and CV between the oxygen group and the control group both preoperatively and 24 hours postoperatively. The results revealed a significant decrease in both CCT and CV in the oxygen group compared to the control group at 24 hours postoperatively, demonstrating statistical significance (Table 3). This finding suggested a notably lower degree of corneal edema in the oxygen group 24 hours after surgery, highlighting the beneficial impact of postoperative nasal oxygen therapy in mitigating the severity of early-stage corneal edema.

Currently, slit lamp microscopy is commonly employed for corneal transparency observation, primarily relying on the observer’s clinical experience. However, obtaining objective quantitative evaluation results for mild corneal edema that remains undetectable under the slit lamp is often unattainable. The Pentacam (Oculus, Wetzlar, Germany) utilizes a rotating Scheimpflug camera for corneal tomography, employing density measurement to quantitatively assess the extent of corneal edema. In our study, we introduced the Scheimpflug camera which utilizes light scattering principles to analyze optical density and represents measured density using gray values. COD values offer a quantitative assessment of mild corneal edema, which is challenging to evaluate through slit lamp examination. Additionally, it facilitates the analysis of different cell layers, aiding in early post-cataract surgery corneal condition assessment. This approach allows for intuitive and rapid evaluation of corneal transparency while also offering easier tracking and ensuring safety through its noninvasive nature.[9] In this study, we compared overall COD values, COD values within different diameter ranges centered on the corneal vertex, and COD values within different thickness layers before and after surgery. The results indicated statistically significant differences in overall COD values, COD values within the 0-2 mm and 2-6 mm diameter ranges centered on the corneal vertex, and COD values within the anterior layer (120 μm thickness) (Tables 4–6). This finding suggested that nasal oxygen therapy could effectively reduce the severity of early-stage corneal edema. In contrast, COD values in the central layer and posterior layer (60 μm thickness) did not show statistical significance (Table 6). We hypothesized that this might be due to the proximity of this region to the corneal endothelial cell layer, where the loss of pump function was partial. Therefore, the damage to the corneal stroma near the corneal endothelial layer was less than that in the anterior layers, leading to no statistically significant differences in COD values at 24 hours postoperatively. Given the significant differences in the anterior layer (120 μm thickness), we speculated that early post-cataract surgery corneal edema was more pronounced in the corneal epithelial and central corneal areas compared to the corneal endothelial layer. Additionally, early intervention to damaged corneal endothelial cells to restore pump function could alleviate the severity of corneal edema and shorten its resolution time.

In summary, our results indicated that immediate postoperative nasal oxygen inhalation for 6 hours could mitigate the severity of corneal edema in patients with cataracts of grades 3 or 4. Additionally, nasal oxygen therapy offers a promising noninvasive approach for the management of postoperative corneal edema, with potential benefits that extend beyond the clinical setting. Its practical significance lies in its cost-effectiveness and accessibility. Compared to more invasive treatments, nasal oxygen therapy requires minimal equipment and is relatively inexpensive, making it an attractive option for healthcare systems with limited resources. Furthermore, the ease of administration and the low risk profile contribute to its wide applicability, even in regions with less developed medical infrastructure. By enhancing the oxygen supply to the cornea in a noninvasive manner, nasal oxygen therapy may not only improve patient comfort and compliance but also reduce the overall burden on healthcare providers and systems.

However, this study had certain limitations. Firstly, the current study has a limitation in its temporal scope, as it only investigated the effects of nasal oxygen therapy on corneal edema within the first 24 hours postoperatively. This narrow time frame does not allow for the assessment of the therapy’s long-term efficacy and impact on the structural integrity of the cornea, such as the long-term effects on corneal endothelial cell density and morphology. Future studies should extend the observation period to encompass a more comprehensive evaluation of the therapy’s sustained benefits and potential late-onset adverse effects. Secondly, the generalizability of the study’s findings is limited by the specific patient population and settings in which the research was conducted. Further research in different clinical settings and diverse patient demographics is essential to validate the applicability of these results across broader patient groups and to explore any variations in treatment response that may be influenced by factors such as age, ethnicity, or comorbidities.

Acknowledgments

We would like to give our great acknowledgments to Professor Haixia Zhang of the Capital Medical University for her supports.

Author contributions

Conceptualization: Chenming Zhang, Aijun Deng.

Funding acquisition: Aijun Deng.

Investigation: Guangguo Dong.

Methodology: Guangguo Dong, Zhongkai Hao.

Project administration: Guangguo Dong, Zhongkai Hao.

Resources: Zhongkai Hao, Chenming Zhang.

Supervision: Chenming Zhang, Aijun Deng.

Writing – original draft: Guangguo Dong

Writing – review & editing: Guangguo Dong, Zhongkai Hao, Chenming Zhang, Aijun Deng.

Abbreviations:

CCT central corneal thickness

COD corneal optical density

CV corneal volume

The study was supported by Jinan Science and Technology Bureau (202225058).

The authors have no conflicts of interest to disclose.

The datasets generated during and/or analyzed during the current study are available from the corresponding author on reasonable request.

How to cite this article: Dong G, Hao Z, Zhang C, Deng A. The impact of postoperative nasal oxygen therapy on early-stage corneal edema in cataract patients with dynamic Scheimpflug analyze: A retrospective study. Medicine 2024;103:37(e39588).
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