Evaluation of Variations of Optic Nerve Course in Relation to Posterior Paranasal Sinuses in MDCT at a Tertiary Care Center of Nepal
Conditions: Optic Nerve
Sponsor: Grande International Hospital, Nepal

GIH-IRC Research Proposal Approval Format- Form A 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Research Title:  Evaluation Of Variations Of Optic Nerve Course In Relation To 
Posterior Paranasal Sinuses In MDCT In A Tertiary Care Center Of Nepal 
 
NCT Number: NCT06077929 
 
Date Of Document: 30th July, 2023 
 
 
 

GIH-IRC Research Proposal Approval Format- Form A 
The applicant should confirm that following supporting information are included during 
application for IRC approval 
 
SN Documents 
Enclosed 
Yes/No/NA 
1. 
Covering Letter addressing to the member secretary indicating the submission 
of the approval of proposal 
 Yes 
2. 
Protocol (Form A) of the intended study  
Yes 
3. 
References- list cited literatures (Minimum 5 References) 
Yes 
4. 
Declaration by Principal Investigator- Funding, Conflict of interest, Approval 
from department/institution 
Yes 
5 
Financial Information (Budget)  
Yes 
6. 
Sample of Consent Form (In Nepali Language too) 
NA 
7. 
Data Collection Instruments/Questionnaires (In Nepali language, if applicable) 
Yes 
8. 
Curriculum vitae of principal investigator and Co-PIs 
Yes 
9. 
Drugs and devices, including copy of DDA approval for Unregistered drugs 
NA 
NA=Not applicable 
 
 
 
 
   
 
 
 
 
   
 
 
 
 
 
   
 
 
 
 
   
 
 
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Registration Date: 
 
 
 
 
  
 
 
 
 
 
 
   
    Registration Number:  
Expedited review: 
 
 
 
 
  
 
 
 
 
 
                     Full house review:  
Name of Reviewer 1:  
Name of Reviewer 2:  
 
 
Duration of Project: 
Department:   
Approved Date:    
 
 
 
 
  
 
 
 
 
 
 
 
 
 

GIH-IRC Research Proposal Approval Format- Form A 
 
 
 
Research Proposal (Use additional sheet if necessary) 
 
1. Title of the research: EVALUATION OF VARIATIONS OF OPTIC NERVE COURSE IN RELATION TO 
POSTERIOR PARANASAL SINUSES IN MDCT IN A TERTIARY CARE CENTER OF NEPAL 
 
2. Introduction: (300 words) 
A. Background: Optic nerve (ON) originates from eyeball and terminates in the brain. It has 
intraconal course, extraconal course and intracranial course. Extraconal course of optic 
nerve shows variations in population. Relationship of optic nerve with posterior paranasal 
sinus (ethmoid and sphenoid sinuses) are of great clinical importance. Most commonly, ON 
is supero-lateral to the sphenoid sinus. However, varied protrusion of ON into the posterior 
paranasal sinuses are seen. Most important of them is onodi cells. If the optic nerve lies just 
lateral to posterior ethmoid cells, the ethmoid cell is called onodi cell. During endoscopic 
sinus surgery (ESS), there is high chance of injury to optic nerve if there is optic nerve.  
According to DeLano classification, there are four types of optic nerve course. Type -I: optic 
nerve is supero-lateral to sphenoid sinus, Type 2: ON courses superior to sphenoid sinus 
with less than 50% indentation in coronal section, Type 3: ON courses superior to sphenoid 
sinus with more than 50% indentation in coronal section. Type 4: ON is just lateral to 
ethmoid and sphenoid sinuses (i.e., Onodi cell). While coursing posterior paranasal sinuses, 
the optic nerves show dehiscence. The optic nerve is encased by dura and thin periosteum. 
The periosteum might not be present in all cases and while coursing through the sinuses, 
they are exposed open. These kinds of optic nerves are prone to injury during ESS. Thus, it 
is imperative to know prevalence of different types of course of optic nerve and dehiscence 
of optic nerve while coursing through posterior paranasal sinuses. 
B. Rationale of Study/ Justification: 
The variants of optic nerve course in relation to posterior paranasal sinuses are of clinical 
importance since some of the variants are prone to injury of optic nerve during functional 
endoscopic sinus surgery. Prior knowledge of course of optic nerve is of utmost importance 

GIH-IRC Research Proposal Approval Format- Form A 
in order to prevent injury of optic nerves. However, there is lack of such kind of study in 
Nepal. Thus, it is imperative to know true prevalence of different anatomical variants of 
optic nerve course. 
 
 
 
 
C. Objectives of the study:  
General objective: To describe different course of optic nerve in relation to posterior 
paranasal sinuses and optic nerve dehiscence in MDCT. 
 
Specific objective:  
• To obtain the prevalence of different types of course of optic nerves according to 
DeLano classification in the MDCT of patients visiting our hospital.  According to 
DeLano classification, there are four types of optic nerve course. Type -I: optic 
nerve is supero-lateral to sphenoid sinus, Type 2: ON courses superior to sphenoid 
sinus with less than 50% indentation in coronal section, Type 3: ON courses 
superior to sphenoid sinus with more than 50% indentation in coronal section. 
Type 4: ON is just lateral to ethmoid and sphenoid sinuses (i.e., Onodi cell).  
• To obtain prevalence of optic nerve dehiscence in the MDCT of patients visiting 
our hospital. 
• To obtain prevalence of pneumatized anterior clinoid process in the MDCT of 
patients visiting our hospital. 
  
 
3. Literature Review with References (relevant up to five) 
In a study by Itagi et al(1), in Indian ethnics, 200 optic nerve canals were assessed and grouped 
into four types based on the modification of Delano et al. classification.  The most common optic 
nerve course (ONC) was Type-1 (60%), followed by Type-2 (15%), Type-3 (14%) and Type-4 
(11%). Dehiscence was seen in 35(17.5%) mostly in Type-3 canals. Pneumatized anterior clinoid 
process (PACP) was seen in 30 (15%). In another study by BN Ravindra et al(2), in population of 

GIH-IRC Research Proposal Approval Format- Form A 
Karnataka, Type 1, Type 2, Type 3, and Type 4 optic nerves was present in 83.33%, 8.87%. 12.1%, 
and 21.78% respectively. Bilateral Type 1 optic nerves was present in 58.88% patients, both Type 
2 and Type 3 optic nerves were seen bilaterally in 3.23% of patients and bilateral Type 4 optic 
nerve was seen in 10 (8.06%) cases. Optic nerve Type 1 (83.88%) was the most frequent nerve 
type, followed by Type 4 (21.78%).  In another study done by Braggs et al(3) in south Indian 
population, type 1 had a prevalence of 61.8%, type 2 had a prevalence of 17.8%, type 3 had a 
prevalence of 7.6%, type 4 had a prevalence of 12.8%. In another study done by Lakhani Mubina 
et al(4) type 1 ON was found to be the most frequent type; 55.93%, followed by type 2 with a 
frequency of 26.85%. However, type 3 and type 4 appeared less frequently, that is 11.1% and 
6.11%, respectively. When comparing right and left sides it was noted that the frequency of type 
1 optic nerve was found to be higher on both right and left sides with a value of 56.30% and 55.5%, 
respectively. Type 2 showed a frequency of 26.67% on right side and 27% on left side. Type 3 
was identified to be 11.4% and 10.7% on right and left sides, respectively. Type 4 optic nerve was 
found to be the least common type in our study on both sides, i.e., 5.56% on the right side and 
6.67% on the left side.  
 
 
Bibliography 
1. Itagi RM, Adiga CP, Kalenahalli K, Goolahally L, Gyanchandani M. Optic Nerve Canal 
Relation to Posterior Paranasal Sinuses in Indian Ethnics: Review and Objective 
Classification. J Clin Diagn Res JCDR. 2017 Apr;11(4):TC01–3.  
2. Bn R, C D. Evaluation of optic nerve variations in relation to posterior paranasal sinuses 
among study population of Mandya District of Karnataka State. Int J Radiol Diagn Imaging. 
2020 Jul 1;3(3):16–20.  
3. Braggs A, S KK. CT Study of Relationship of Optic Nerve to Posterior Paranasal Sinuses. Int 
J Contemp Med Surg Radiol [Internet]. 2018 Dec [cited 2023 Jun 27];3(4). Available from: 
https://www.ijcmsr.com/uploads/1/0/2/7/102704056/ijcmsr_161.pdf 
4. Mubina Lakhani, Muhammad Ali, Madeeha Sadiq. Analysis of Optic Nerve Types in Relation 
to Posterior Paranasal Sinuses: A Computed Tomographic (CT) Study. Ann ABBASI 
SHAHEED Hosp KARACHI Med Dent Coll. 2017 Dec 31;22(4):249–54.  
 
 
4. Research Methodology: 

GIH-IRC Research Proposal Approval Format- Form A 
A. Study type: Quantitative Study 
B. Study design:  Retrospective Cross Sectional Observational Descriptive Study 
C. Sample size:  Minimum 319 patient’s CT scan; The size was calculated by the 
following formula for sample size: 
n= Z2 P (1-P)/ d2 , Where: 
Z- 2.576 (for 99 percent confidence interval) 
P- Prevalence of most common anatomical variant from previous study (60 %) 
d- margin of error (5%). 
 
Calculation: (2.576 x 2.576 x 0.6 x 0.4) / (0.05 x 0.05) = 637 optic nerve canals 
(Since 1 patient has 2 optic nerve canals, number of CT to be studied =319) 
D. Inclusion and Exclusion Criteria: All MDCT scan of PNS referred for evaluation of 
chronic rhinosinusitis and nasal polyposis and Head referred for evaluation of 
headache, dizziness, loss of consciousness in patients >13 years age are included in 
the study. MDCT PNS and head done for evaluation of trauma and tumors are 
excluded from the study. 
E. Data collection methods/tools: Images will be studied and findings will be recorded in 
predesigned Proforma. The proforma is attached herewith. 
F. Data analysis methods/tools: Prevalence of the variations of optic nerve course was 
calculated by using previous study in Indian population and free software like epi 
info. 
 
 
 
 
 
 
 
5. Work plan/GANTT chart (start, progression, completion time for study/research) and 
Budgeting.  
 

GIH-IRC Research Proposal Approval Format- Form A 
 
S 
N 
Tasks 
From 
To  
 
August  
September October November 
1 
Extraction of 
data 
1 August 
31 August  
 
 
 
2 
Study of data 
and 
categorization 
1 
September 
30 
September 
 
 
 
 
3 
Data analysis 
and obtaining 
result 
1 October 
31 
October 
 
 
 
 
 
4 
Preparing 
Manuscript 
1 
November 
30 
November 
 
 
 
 
 
Total duration of study will be of 4 months after the approval. 
Funds will be generated from the involved investigators. 
First month- Extraction of data from August 1 to August 31 2023 
Second month- Study of the data collected and categorized accordingly. 
Third month- Data analysis and obtaining the results 
Fourth month- Preparing Manuscript. 
 
 
 
 
BUDGET 
 
 
ITEMS 
Unit 
Price per unit 
APPROXIMATE 
COST 
Stationary 
 
 
Rs. 1000 

GIH-IRC Research Proposal Approval Format- Form A 
Statistician 
 
 
Rs. 5000 
Miscellaneous 
 
 
Rs. 5000 
TOTAL 
 
 
Rs. 11000 
 
 
 
 
 
 
 
Declaration (Please tick) 
S.no 
Title 
Yes 
No 
1.  
Are foreign researcher / institutions involved in the research? 
 
No 
2. 
Is your research being funded by organization or agency? 
 
No 
3. 
Are vulnerable members of the population required for this research? 
(Except routine work treatment/observation in hospital set up e.g., 
pediatric, obstetric patient, patient in psychiatric hospital, etc.)  
 
No 
4. 
Are there significant risks involved for the participants? 
 
No 
If any of the declaration is "yes" then please fill up the form "B" with supplemental detail 
information. 
 
Declaration by the principal investigator 
 
I hereby certify that the above-mentioned statements are true. I have read and understood the 
regulation of the Nepal Health Research Council (NHRC) and will act accordingly.   
 
If the research is terminated, for any reason, I will notify IRC-GIH of this decision and provide 
the reasons for such actions.  I will provide a written notice upon the completion of the research 

GIH-IRC Research Proposal Approval Format- Form A 
as well as a final summary/full report of the research study.  For publication in a journal, I shall 
acknowledge the IRC-GIH approval and shall provide the committee copy of such publication. 
 
Full name (first/middle/last):   Dr Prajwal Dahal 
 
 
(Signature)  
 
Date: 10/07/2023 
Email: meprajwal7@gmail.com  
 
 
 
 
 
 
Contact No: (preferably mobile no) : 9841948177 
 
 
 
 
Data Collecting Instrument of the study ‘EVALUATION OF VARIATIONS OF OPTIC 
NERVE COURSE IN RELATION TO POSTERIOR PARANASAL SINUSES IN MDCT IN A 
TERTIARY CARE CENTER OF NEPAL’ 
 
 
 
Name:                                                                                         Age:                      
 
 
Sex:                                                                                             Date: 
 
 
 
 
1)Course of optic nerve: Right:                                              Left:  
 
2)Wall dehiscence of ON: Right side (Present, absent); Left side (Present, absent) 
 
 
3)Pneumatization of anterior clinoid process: Right side (Present, absent); Left 
side (Present, absent)